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PHOIBOS

1. 68 p metal shielding 5 20p VII Index SPACS PHOIBOS E Health and Safety Declaration for used Vacuum Equipment and Components The repair and or service of vacuum equipment components can only be carried out if a correctly completed declaration has been submitted for every component 1 Description of components Type Serial No 2 Reasons for return 3 Equipment condition Has the equipment ever come into contact with the following e g gases liquids evaporation products sputtering products Yes No e toxic substances Q M corrosive substances u u microbiological substances incl sample material u m e radioactive substances incl sample material u m ionising particles radiation o D y neutrons u M Yes No Is the equipment free from potentially harmful and hazardous m substances 4 Decontamination Procedure Please list all harmful substances gases and by products which have come into contact with the vacu um equipment component during the decontamination methode used SUBSTANCE DECONTAMINATION METHODE 5 Legally Binding Declaration Organisation Address Phone Fax Name Position hereby declare that the information supplied on this form is complete and accurate Date Signature Company stamp Rev 0 1 1
2. sess nnt rines n nnn 38 Corresponding Hole in the Ground Plate 39 Mounting Mgo f EE 42 D tector Flange su ttn meret FR ai TEESE EE UR SEA EER UNE TEETE eects 43 Starting up the detector uiui rage Se nice eae ei epoca ec doc HERE bains deeds 48 Menu Analyzer Settings ieusssssssssssssessssseseeeennee enne eene rennes ninh nnn nnnnern nnne nnn 58 Analyzer Cailbration Procedure seessssssssssseeeeeeenee nennen nnne enne nnne nnns nnn nnn 59 auepse ilec iile 60 Fermi Edge Operation ini rtis oix rara pu E ed Ra ET cane aaka cura Vo rude ad 62 FenmlEAGE OPGratlOm EE EE TEE DIE 63 XPS on Silver Wide Scan PHOIBOS 150 MCD J9 cceeeennm ennemis 68 XPS on Silver Ag 3d PHOIBOS 150 MCD9 ssessssssseeeeeenenenen nennen nennen 70 Schematics of the 12 pin Analyzer Feedthrough ssessssssesseeeeeeneeenn nen 72 Schematics of the 12 pin Detector Feedthrough ssssssssseseeeeneeeeneee nenne 73 e UI YT Du Tal f RE 76 CounterChannelMask for MCD9 1424849 off nennen eene nnns nnn 78 Screws fixing the ceramic rods and adjustment crew sssssssssseeeeeenn 83 Pull back the Ceramic Rods Remove the Channeltron ccccccccccceceecesesssseeceeeeeseeeeeeeseeeees 83 l List of Figures S PEC S Figure 39 Align m nt d Ta ARM 84 II PHOIBOS S P E CS Vistonigures o SPECS Chapter
3. Compete nee Surface Analysis Vacuum Surface Analysis Computer Technology Components P System Software Technology PHOIBOS Hemispherical Energy Analyzer Series PHOIBOS 100 PHOIBOS 150 3 1 SPECS All rights reserved No part of this manual may be reproduced without the prior permission of SPECS GmbH User manual for the Hemispherical Energy Analyzer Series PHOIBOS 100 150 Version 3 1 revised 19 November 2008 SPECS order number for this manual 78 000 101 SPECS GmbH Surface Analysis and Computer Technology Voltastrasse 5 13355 Berlin GERMANY PHONE 49 0 30 46 78 24 0 FAX 49 0 30 4 64 20 83 http www specs de PHOIBOS SPACS Table of Contents 1 Introduction 1 Um B Old ne a ne a ET 1 2 Components and Connections 5 2 1 System Description Package Contents s 5 2 2 Electrical CONNECtIONS 0 ceeecceceeecceeeececeeccecceeeceeecueeaeeeaeeceeeens 6 3 Spectrometer 11 3 1 TNE Le s System iik o EUR EXE CUu GUERRE Ma VERG 12 3 2 Hemispherical Analyzer HSA c cccceeeeeceeeecceeceeeeeeeceeeaeees 18 3 3 Magnetic Shielding esssesssssseseeeeeee nnne nnne 20 3 3 1 Magnetic Coupling for p Metal Chambers seseeeeeees 21 3 3 2 TAM Sell NITET EE 21 3 4 Slit Orbit MechabistTissiesasxvixxc tna pou 2exU ES EXXR dA FE YE MR KR I a a ia 22 3 5 Single and Multichannel
4. Customized Length PHOIBOS Electrical Connections SPECS Viewport for Alignment 280 ji i DN500CF moor ee TET ri ee T ar E ILI i at e pum ELT EICELLL Rotary Device 9 Uns m m for Iris ULT uu Amn g mee v Aperture E ret not visible Mounting Lug M12 DN150CF a LI JEL LII m LLLI LLLI D i Electrical Feedthrough i eo eee Additional Pumping Port DN63CF P Variable Slit Drive Fa DN150CF P4 I m D i SE DN100CF tapped 095 E oS Dio Te 2 e 2 E U Sample L1 Weight approx 100kg L Dimensions in mm 44 Figure 4 Analyzer Housing PHOIBOS150 PHOIBOS Components and Connections S P E C S R 10 Lens system Hemispherical capacitor with radii 660 mm d 3500V 1500V Chanrfel A nannel Base 400V 40V Figure 5 Analyzer Main Components and Voltage Principle UO main retardation voltage numerically equal to kinetic energy Ekin pass energy Ep workfunction WF UChannel HV Base
5. SPECS Chapter Analyzer Checks 8 1 Independence of Peak Position with Pass Energy Because of the large number of slit and lens combinations the energy calibration of the analyzer was not done for each slit combination SPECS delivers the analyzer with the correct parameters for the common slit combinations To check the independence of the peak position with pass energy for a desired slit combination please follow the pro cedure below Transfer a silver sample into the system Warm up your electronics first Adjustments Excitation Mg Ka X ray power 100 W Slit desired slit combination e g entrance largest slit exit open Mode Medium Area Binding energy range 365 375 eV Scan 1 Dwell Time 100 msec Energy step 25 30 meV Pass energy 15eV Run a spectrum Set a second pass energy for the above described slit combination e g of about 5 eV Repeat the measurement Compare the spectra If the voltages are cor rect the peak maxima of both spectra have to have the same energy The peak posi tions of both spectra should not differ by more than 100 meV For a symmetrical peak the peak position is independent of Epass This is not true for Auger electron peaks since the peaks are intrinsically asymmetrical You can also display the single channels for the accumulated spectra The difference in the peak maxima for each channel indicates the quality of the MCD Calibration see sec tion 7 3 If the peak energy weakly d
6. sputter cleaning replace anode lateral inhomogeneous charging of the sample use charge compensation by means of elec tron flood gun noise or and ripple on the following voltages sample spectrometer voltage UO detector voltage electrode voltages of the analyzer ground sample and check hum and ripple check the ground connection of all the power supplies gt section 4 7 magnetic fields in the region of the spheres measure magnetic field preamplifier setting changed check preamp setting gt section 3 5 3 lens system and HSA out of focus check lens and HSA electrodes gt section 8 4 and voltages section detector supply voltage incorrect check detector supply voltages section carbon coating of HSA spheres damaged open HSA and check do this only if all other checks are negative Humming and ripple on the following parts sample spectrometer voltages multiplier voltage lens voltage ground sample check humming and ripple Table 7 Low Energy Resolution possible cause perform check test or troubleshooting procedure no gt workfunction setting incorrect Check the work function setting section 7 4 sample charging Check the sample ground connection Use ex ternal electron flood gun to compensate for the charging voltages of the HSA inner and outer sphere are incorrect In similar spectra with different pass energies the pe
7. LT List of Tables Table 1 Acceptance Angle vs Iris Diameter for a Point SOUICE cccsccccssseessseeessseeeeeeeeeesesseessennanees 15 Table 2 Overview of the Lens Modes sss nennen nnne nnne tnnt se tnet rentre nanne n nnne 16 Table 3 Recommended Iris Values for Spatially Resolved Measurements 17 Table 4 Standard Slit Configuration essesssssssssssseeseseeeee enne ennt nnns nnns en nsns 23 Table 5 No Specthumics4a c UTERE 52 Table 6 LOW Intensity essssessssesessssseeseeeeee nennen nnns eae eee eae eee 53 Table 7 Low Energy Resolution eene nennen nennen nen nnn seen rnnn nnns nnns nnne nnn nnns 53 Table 8 Peaks Shifted Equally iere reru an eet then n EYE Rx nha yea nk entre Ra te Rap ce De aaa daana 54 Table 9 Peaks Shifted Differently esssssssssssssessseesese enne nnne nennen ntn renes teres sinet nnns nnns 54 Table 10 Intensity Fluctuations ssssssessseseseseeesseseeennen enne nennen nnn nnnn eae eae eae nnns snnt nnn 54 Table 11 High Background Signal eeesssseseseseseseeeene nennen nenne nnn nnmnnnnn nnn nensi nennt nnn nnns 54 Table 12 Noisy Spectrum sssssssssssessseseseeee nennen nennen enter eae eee eee eee eee eee eae eee 55 Table 13 Incorrect area was analyzed in all lens modes sssssseeeeeeneeeennene 55 Table 14 Calibration Binding Energies for non monochromated M
8. The analyzer is evacuated Vent via valve at the protection housing SPECS re commends using a dry dust free venting gas like nitrogen to avoid particle or water intrusion Remove the lens protection housing from the analyzer mount ing flange Do not touch any vacuum parts without gloves Check the working distance of the analyzer 40mm between sample and the top of the lens system gt insertion depth in your chamber Tighten the delivered stay bolts PHOIBOS150 on the analyzer mounting flange and prepare the necessary mounting parts screws for PHOIBOS100 washers and nuts Insert a new DN100CF copper gasket into the vacuum chamber flange Center the analyzer mounting flange above the vacuum chamber flange Introduce the lens system into the vacuum chamber flange very slowly Do not use any force During the introduction check all other components in the vacuum chamber for possible physical damage During the introduction check all other components in the vacuum chamber because of possible physical damage All rotary feed PHOIBOS S PAC e Vacuum Installation PHOIBOS throughs are fixed with the locking screw during transport Make sure to unlock them before using the rotary feedthroughs and lock them again afterwards 13 Adjust the analyzer at the vacuum chamber flange Check section 4 4 Align ment on page 40 14 Bolt the analyzer at the vacuum system flange with the delivered screws wash ers and nuts 15 For PHO
9. Use the SpecsLab mode Detector Voltage Scan and set start end step and dwell time parameter for this procedure During the first few days of operation of a new detector it is recommended that high output currents are avoided i e inputs above 1 Mcps Taking this ini tial burn in precaution can prevent premature failure Choose a moderate value of the detector voltage to prevent rapid ageing of the detector The optimum operating point is about 50 100 V beyond the plateau of the intensity versus detector voltage sweep not more 39 Installation 40 SPECS e Backstreaming from oil diffusion pumps or roughing pumps has to be avoided at all costs It is strictly recommended to use cold traps and molecular sieve traps and maintain them according to manufacturers specifications e Channel electron multipliers can be degraded by exposure to various types of hydrocarbon gases which raises the work function of the surface and hence causing gain degradation Operation in a clean vacuum environment of 5x10 8 mbar or better is a must in order to ensure the long life characteristics of these devices e Other gases containing F S and Cl which may decompose under electron bom bardment must not enter the detector area e Due to the hygroscopic nature of the doped lead glass it is important that the channel electron multipliers are not exposed to air for more than one day Dry nitrogen should be used to vent the system e High inte
10. and fine tuning of the offset for all modules except 40V via Fermi edge measure ments Figure 29 Fermi Edge Operation page 62 and optionally 58 PHOIBOS S PEC S Complete Calibration Procedure PHOIBOS 4 5 Gain calibration with XPS A calibration check for the gain of the 1500V and 3500V modules see section 7 7 on page 64 and in section 8 2 2 Check Peak Position on page 66 verify that the peak po sition in an XPS fit to the modifications of offset and gain performed in the se lected range high precision digital voltmeter For 1500 and 3500 V range you have to use a Software adjustments Calibration procedure Analyzer i e HSA3500 modules calibrated known XPS AES peak difference Gain 400 1500 3500 V gain value usually correct 1 0 Analyzer Settings 3500V module B EREXIT 1500V module bi zum 400V module Offset correction for 400 1500 3500 V saved in Analyzer Settings WF estimated saved in Analyzer Settings adjust offset adjust gain for all modules 1 40V module high voltage probe 1000 1 40V range SL2 measurement offset gain UPS Fermi edge supposed correct slit lens combination SL2 MCD calibration MED deter shi now correct saved in registry done by SPECS Figure 27 Analyzer Cailbration Procedure 7 2 Recalibrate the DAC Precision Note the
11. and O peaks are small enough Otherwise the sample should be sputtered once more 49 Unit Operation S P e C S 8 50 5 3 3 2 ISS Operation Please read these instructions carefully Damage of channeltrons and ampli fier are possible if the following is done incorrectly Set the detector voltage to the value corresponding to the Specification Report of the analyzer or check the actual value The Working Point of the CEM s on page 27 The conversion voltage BIAS in the Analyzer Settings window is default set to 2000 see section 3 5 4 Conversion Energy on page 32 x XPS Voltage Range V Range 1500 UPS Voltage Range V Rages0v AES Voltage Range V Rae3500v ISS Voltage Range V Ranges v m Default Bias Voltage Electrons V n 00 Default Bias Voltage lons V po 48 BIAS Default Detector Voltage V on O O The excitation source should be degassed and run under proper conditions to avoid structures due to possible residual gas inside the sputter line Switch the method to ISS mode in SpecsLab Name Region2 Method Entrance and E fiss 272 20 ISS Recommended lens mode Point Transmission L Region Edit Name Group Analyzer Method Entrance and Exit Slit Lens Mode iss X zat 2ope X MediumPointTransmission Be Eexc Ekin Start LargeArea a roo Miro it NUR oat Point Transmission R MediumM
12. each incident particle releases an electron cloud at the exit of the CEM arrangement whose charge is independent of small changes in multiplier voltage The saturated operation is ne cessary for sufficient noise rejection in single particle detection Usually the minimum gain for saturated operation is about 107 i e an electron cloud of more than 107 electrons leaves the CEM The electron cloud emitted is accelerated onto the collector elec trode of the CEM and the charge pulse carried by the electron cloud is detected as originating from one incident particle and counted in the preamplifier channel One or a set of CEM s is used in a special arrangement as an electron multiplying com ponent for the PHOIBOS analyzers The CEM s are all mounted in parallel as a unit on a feedthrough flange Particles passing the exit aperture are accelerated to an appropri ate kinetic energy onto the CEM The particle energy can be calculated as described in section 3 5 4 Conversion Energy on page 32 The Working Point of the CEM s The operating point for a channel electron multiplier CEM in the pulse counting mode is usually determined by the point at which a plateau is reached in the count rate vs voltage characteristic Within the plateau all electrons collected at the input of the CEM give an electron pulse at the output high enough to be detected by the electronics Additional increases in voltage raise the gain but the count rate remains es
13. A bakeout time between 24 hours and 48 hours first time is recommended After a bakeout the analyzer needs two days to cool down If channeltrons are oper ated at higher temperatures gt 340 K they can suffer damage Some channeltrons will lose gain and exhibit a markedly higher detector plateau The interior parts of the PHOIBOS will cool down significantly slower than the housing It is recommended to wait for a complete cool down of the detector assembly approximately 2 3 days Even if the analyzer housing just feels warm any internal parts seated on isolators may still be too hot for safe operation It is imperative that all users be informed of this issue and take the necessary precautions The multiplier will degas at first operation after bakeout so care should be taken not to use the detector at full multiplier voltage and full intensity within the first few hours after bakeout We recommend increasing the detector voltage over a period of 1 5 hours for the first use and over a period of 10 min for subsequent times after bakeout Use the SpecsLab mode Detector Sweep and set start end step and dwell time para meter for this procedure 4 7 Electronic Units Installation The electronic units have to be installed into a 19 cabinet rack Good air circulation within the cabinet must be ensured For wiring of the electronics follow figure 2 page 7 Note the following 1 Connect all units to the same power strip 2 The power
14. Depending on the type and amount of your chan neltrons you will measure few MQ internal resistance 50 300MQ per channel or chan neltron Note that the channeltrons are connected in parallel 6 2 Possible Problems The following problems may occur during operation of the analyzer system e nospectrum low intensity low resolution peaks shifted intensity fluctuations high background signal noisy spectrum incorrect area analyzed Slit Orbit problems 51 Troubleshooting 52 SPECS An arrow gt after a statement indicates a separate troubleshooting procedure either given here or in another manual Possible Cause perform check test or troubleshooting procedure no gt X Rays off check the X ray source and the sample current No voltage at detector check detector voltages Spectrum definition incorrect check spectrum definition Cable connection faulty check cable connections Preamplifier box defective check preamp box gt section 9 1 2 Counter device or control unit defective contact SPECS No energy sweep voltage check energy sweep gt section and Spectrometer voltages incorrect check spectrometer voltages section Improper adjustment of slit orbit check proper adjustment gt section 3 4 Table 5 No Spectrum possible cause perform check test or troubleshooting procedure no gt X ray intensity too low check
15. Detector SCD MCD 25 35 1 Principles of Detection sssssssssssseseeeeeeennenene enne 25 3 5 2 Coherence of Epass and Step sssesssseeeeeeeeeenneennne nnns 26 3 5 3 Electron Multiplication seseseesssseseeeeeeneeeenn nennen 27 3 5 3 1 Extended CEM rcu cniin tero bep Eee s exor oa Ce cro exa Pea NN EEEREN 29 3 5 3 2 Linearity of the CEM nii ease er ce anban 30 3 5 4 Conversion ENELQY ccccccccccsssseneeeeceseceneeeeeeesseeeaeeeeeesscseeeeeeeeeeeeeeeeeeess 32 3 5 5 Spectrometer Voltage UQ iss sssrinin ianen nnns 33 3 6 WorkPunctioh scri inae exe Ux oak hab bsxuE sd p Ux V QE RRE RU MR ES UE 34 4 Installation 37 4 1 Ungackifiua scr torrrhpa ie e Rima tac REPRE AIR RMA TAPA RU taE a RE UERSR ERE RAE 37 4 2 Mounting the Detector seseeseseeeeeeneeee nnns 37 4 3 Achieve the Maximum Lifetime of a Channel Electron Multi plier 39 PHOIBOS Table of Contents S P E C S Amd ADOGNIEDE seii ori bU oxden ad in aa dud Moa a damus aub iir EIN UE 40 4 4 1 Analyzer Alignment ecce eocic Leer orci ee ceo ern aL sane e cx naui Bacon tore a 40 4 5 Vacuum TAG A AN Oa cocco esesbesa c co oS EEERRa pianta ds het menus 41 46 o Red TNR 43 4 7 Electronic Units Installation eee 44 4 8 SpecsLab Hardware and Software Installation 44 5 Unit Operation 47 S L First Ch a PON acs a va
16. at each collector C is counted separately and these numbers are stored and preprocessed in the data acquisition unit By sweeping the spectrometer voltage U the electron path is moved across each col lector channel step by step and in this way each collector records a complete spectrum with a fixed energy offset between neighbouring channels In principle by sweeping the spectrum once over the detector area 5 or 9 parallel spectra are recorded simultan eously As the kinetic energy En of the particles arriving at collector C is known from equation 16 the number of particles from each channel belonging to the same kinetic energy can simply be added resulting in a total number of particles for each kinetic en ergy 3 5 2 Coherence of E and Step From the analyzer energy dispersion equation the energy difference AEk between neighbouring channels at the distance AR one from another is AR AE 7p pass 18 or D Es p At 19 where D is the analyzer dispersion Especially in the FRR mode where the pass energy changes throughout the spectrum and thus the energy difference between neighbouring channels a calculation of the detected energy of the particle is necessary Therefore a software routine calculates the particle number Nn in channel Cn at the nominal kinetic energy by interpolation between the numbers actually measured in channel Cn at the measuring energies nearest below and nearest above the nominal energy Thi
17. by correcting the Work Function sections 7 4 Work Function Calibration with UPS on page 61 7 5 Work Function Calibration with XPS on page 62 or 7 7 Gain Calibration with XPS on page 64 If this is not the reason a complete calibration as described at the begin ning of this chapter is required or there is a failure in the analyzer or supply chapter 6 Troubleshooting on page 51 Note Strong displacement usually caused by poor contact inside the analyzer see Connection check for the analyzer electrodes on page 70 or control unit failure see Control Unit Check on page 61 Peak Mg Ko Al Ka Binding Energy eV Binding Energy eV Au 4f7 2 84 00 0 01 83 98 0 02 Ag 3d5 2 368 27 0 01 368 26 0 02 Cu 2p3 2 932 66 0 02 932 67 0 02 2 XPS Binding Energy Calibration of Electron Spectrometers 5 Re evaluation of the Reference Energies M P Seah I S Gilman and G Beamson Surfaceand Interface Analysis 26 642 649 1998 66 PHOIBOS S P E C S R Energy Scale Tests with XPS PHOIBOS Cu L3MM 334 94 0 01 567 96 0 02 Table 14 Calibration Binding Energies for non monochromated Mg Ka X rays 8 3 Specification Check 8 3 1 Survey Spectrum of Silver The XPS performance of an energy analyzer is usually determined using a silver sample A clean silver sample is introduced into the vacuum chamber and cleaned by ion sput tering Use the same settings as in the overview spectr
18. make the sampling area of the analyzer and the acceptance angle area of the lens selectable Thus the analyzer allows spatially resolved measurements down to a diameter of 100 um as well as large area investigations associ ated with different lens acceptance angles All units are completely controlled by SPECS software Operation of the software will be described in a separate manual Typical uses of the PHOIBOS analyzer include photoelectron spectroscopy XPS SSXPS UPS Auger electron spectroscopy AES SAM and ion scattering spectroscopy ISS The PHOIBOS analyzer is bakeable up to 200 C after removal of the detector electronics and the connection for the lens supply 2 PHOIBOS S p E C S Overview Safety Information Before any electric or electronic operations please consult SPECS Safety Instructions and follow them strictly Some adjustments that have to be performed in this manual are dangerous At each point these are indicated by a warning label Warning Tests to be performed on the electronic unit are with its cover removed Hazardous voltages are present Only trained qualified personnel are allowed to perform this task PHOIBOS 3 Introduction S P E C S R 4 PHOIBOS SPECS Chapter Components and Connections 2 1 System Description Package Contents The contents of your system should include the components listed below Please refer to figure 1 for photos of these e PHOIBOS analyzer T
19. manually perform the recalibration of the DACs section 7 2 on page 59 2 Set the voltage range for the UPS measurement mode in the Menu Analyzer Settings see Figure 26 to 40V 3 Switch to the binding energy scale Measure the position of the fermi edge e g 0 2 to 0 2 eV binding energy and select Hel if He of course is used in the dummy source of the Menu Analyzer Settings Sources selected The tool Op eration Fermi Edge in the SpecsLab2 program as well as the cursor and differ ence cursor cross black red cross icon left right mouse button simplifies the procedure 4 Calculate the energy difference between expected and measured fermi edge 5 Note that the high precision measurement with the digital voltmeter for offset and gain are considered as correct and therefore especially for the 40 V mod ule no further change for offset and gain is recommended Once the measured values for this range are correct than it is possibile to estimate the work func tion Correct the default work function value in the Menu Analyzer Settings If the measured difference should be larger than 50meV perform the measure ment as described in section on page and change the values Note that 61 Calibration 62 SPACS voltmeter precision and poor grounding of the sample can falsify the calibra tion The work function correction will be applied to all modules 6 Check the result with new spectra Ba Ed de
20. power supply needs time to warm up A self calibration procedure for the DACs is run every time the power is switched on You should restart the DAC calibration procedure after a warm up 5 15min switch off on or use the field Recalibrate DAC Precision in the menu Analyzer Settings figure 26 page 58 Temperature stability as Calibration 60 SPACS well as sample charging or contamination of the surfaces inside the analyzer can influ ence your calibration Perform a manual Recalibrate DAC procedure to increase the accuracy to the possible maximum if you have already warmed up the supply for at least 1 hour e g type in a value of 64 7 3 MCD Calibration SpecsLab2 software supports a calibration procedure named MCD Calibration in the Tools menu The procedure should be used for the calibration of single channel de tectors also Because of the energy shift between the single channels for a given kinet ic energy section 3 2 Hemispherical Analyzer HSA on page 18 and the depend ence of the transmitted energy range of a acceptance angle see equation 5 page 18 the detector shifts are different for each lens slit combination For the most common lens slit combinations the values defined by SPECS and implemented in the software give a good approximation Nevertheless the most commonly used lens slit combina tions should be calibrated by the customer again to prevent loss of performance You can easily ch
21. this increase the discriminator level to about 15mV or use a resistor of about 100 Ohm for the check The default detector threshold is between 2 and 10mV Do not forget to set the discriminator back to the original or desired values 9 2 Detector Voltage Because of a considerable spread in the gain of different multipliers and the threshold level used the voltage required for the signal for the installed detection system may differ Pay attention to the detector voltage value in the Specification Report sent with the analyzer Basically a working detector voltage is the detector voltage at the begin ning of the detector plateau DetectorVoltageScan see Figure 15 Detector Sweep Count rate vs Voltage page 30 and has to be checked monthly PHOIBOS S P CS ui PHOIBOS 9 3 Noise Depending on the environment of the analyzer ground feedthrough connection status the handling during transport installation bake out dust and the his tory of of operation vacuum gas load total amount of accumulated charged particles etc some or all channels may show noise without any excitation If the Amplifier Check on page 80 shows that the amplifier is working correctly the grounding of the analyzer is ok by following the advice given in sections 3 5 Single and Multichannel Detector SCD MCD on page 25 and in section 9 1 1 Discriminator on page 75 the noisy channels can be suppressed First try to set the
22. to the pass energies in such a way that the maximum intensities in counts not in counts per second are about the same in every case Namely for low pass energies choose a higher Dwell Time than for high pass energies This gives comparable counting statistics for all measurements 69 Analyzer Checks 70 Bo i PHOIBOS Hemispherical Energy A s gr lemispl nergy Analyzer S PE C S LAB 885 311 Friday January 18 2002 16 53 23 Y Kinetic Energy eV JEkomponen ten phoibos T50 Work WwmanualsiBilderips ban Group Region Method Lens Str Mode Scans Fae Ekin IOW MA9 XPS 2 7x20220pen FAT 1 1253 6 870 893 01 Paget Figure 32 XPS on Silver Ag 3d PHOIBOS 150 MCD9 Parameter for the Ag 3d spectrum in figure 34 Lens mode Medium Area Slit 2 7 x 20 mm 2 open Sample current 160 nA 300W Mg Ka Detector voltage 1950 V If no spectrum but a straight line appears after the control unit has been started either no pulses are arriving at the control unit counter the counter is defective or the spec trometer voltage Uo is missing The following checks should be made 1 2 3 4 8 4 All cable connections Figure 2 Connection Scheme page 7 between has 3500 and Detection box PCU 300 the computer and the EC10 Ethernet Can Adapter Control Unit Check see section Preamplifier see section 9 1 Section 9
23. voltage see section 9 1 1 Discriminator on page 79 Large differences between the channels can be equalized by setting the threshold for the channels individually These differences may be caused by the varying sensitivities of the CEM s Pay attention to the detector voltage value in the Specification Report sent with the analyzer The detector check should be done monthly choose kinetic energy of 400eV PHOIBOS S P E C S amp Single and Multichannel Detector SCD MCD ZEE BEE Nent Page Liv F a Iwo Page Zoomin 555v Gee PHOIBOS Hemispherical Energy Analyzer S P E C S LAB ad Thursday Janvary 10 2002 17 53 25 T 1850V Intensity 103 Cps 1 6 Detector Voltage 107 v J komponen ten phoibos 15 O work manuals Bilder xps bin Group Region Method Lens Slit Mode Scans Dwell Delta User Comment Detector Detectorscan 100W XPS MA 1 6x20 6x20 DVS 1 0 1 110 1000 2200 100W 50nA PHOIBOS 1897 fv 231800 Figure 15 Detector Sweep Count rate vs Voltage The pulse output depends largely on the applied voltage and in practice the gain is an increasing function of the applied voltage until the gain reaches about 10 after which point increasing the voltage further will cause the eventual breakdown of the CEM With a properly configured oscilloscope i e impedance 50 Ohm the neces
24. 00 Longitudinal Distance mm 30 Retarding Ratio 10 Iris Aperture Plane Intermediate Plane Disc of Least Confusion Analyzer Entrance Plane 0 200 400 Longitudinal Distance mm Figure 8 High Magnification Mode Acceptance lris Angle Diameter x1 3 5mm 2 7mm 3 10mm 4 13mm 5 15 5mm 6 17 5mm 600 Table 1 Acceptance Angle vs Iris Diameter for a Point Source In the novel angle resolved Medium Area mode electrons leaving the sample within a given angular range are focused onto the same location of the analyzer entrance inde pendent of their position on the sample The angular modes allow the user to optimize the angular resolution down to 0 05 with the Slit Orbit mechanism With a 2 D de tection system high angular resolution can be achieved in the dispersion direction of 15 Spectrometer 16 SPECS the analyzer without restricting the acceptance angle this mode is the ideal choice for angular dependent studies Magnification and angular aperture are selectable with PHOIBOS There are many dif ferent combinations available The lens settings can be combined with the different possible slit combinations resulting in lens settings x number of slits possible com binations The analyzer sampling areas and input lens acceptance angles for these com binations is given in table 2 The table sho
25. 2 Detector Voltage on page 76 Connection Check of the Analyzer Electrodes In addition to this test the correct generation of the spectrometer voltages should be checked see section on page PHOIBOS S P E C S R Connection Check of the Analyzer Electrodes PHOIBOS 8 4 1 Capacitance Check for Electrodes Check the electrode connection to the electrical feedthrough For this check a capacit ance meter must be used The best way to check is to measure the capacitances between the housing and all pins of the feedthrough of the analyzer see Figure 33 Schematics of the 12 pin Analyzer Feedthrough page 72 Switch off the HSA 3500 and remove the connector to the HSA electrodes Mind the safety information given at the beginning of this manual The capacitances measured on the HSA and lens electrodes under UHV conditions in table 16 and table 17 are for information only Some differences caused by the meter should be taken into consideration when checking the values Correct ratios between the values show correct connection to the analyzer parts the absolute values may differ from the values in the table Tables of former releases can be found in the documents Check PHOIBOSRx pdf PIN 1 2 3 4 5 6 7 8 9 10 11 12 housing 32 147 123 37 121 l 65 71 323 62 170 Table 15 Capacitance Measurements pF PHOIBOS100 R6 or higher PIN 1 2 3 4 5 6 7 8 9 10 11 12 housing 60 191 13
26. 9 63 124 l 71 79 396 109 303 Table 16 Capacitance Measurements pF PHOIBOS150 R6 or higher If the measured capacitances differ substantially from the nominal values please contact SPECS If the capacitances have nearly the right values no short circuit inside the spec trometer is likely If the measured capacitances have the correct values a missing con tact from the HSA 3500 to the analyzer may be the reason for a faulty spectrum see section 8 4 2 on page 71 8 4 2 Check the Cable Contacts The connection to the analyzer and the detector are supplied by two multi pin vacuum feedthroughs which are designed for high voltages up to 5 kV Check whether the con tacts are in good condition Since the plug is a movable part which is frequently plugged and unplugged it can become defective In most cases contact failures in the plug are the reason e A 12 pin feedthrough on a flange DN38CF mounted to the lens housing for all voltages of lens electrodes and capacitor electrodes which is schematically shown in figure 33 page 72 e The second 12 pin feedthrough DN38CF mounted at the detector flange for all channeltron voltages and channeltron outputs The pin assignments is shown in figure 33 page 72 71 Analyzer Checks SPECS view from atmospheric side PIN 1 PIN 2 PIN 3 PIN 4 PIN 5 PIN 6 PIN 7 PIN 8 PIN 9 Inner Jost Plate Tubus 2 Tubus 3 O
27. IBOS150 and metal chambers Do not release the lifting gear until the analyzer is supported by an additional supporting post 16 Check the physical stability of the supporting post and the system frame and re lease the lifting gear 17 Use the iris aperture and the analyzer view port to locate the real center posi tion of the lens with respect to the desired acceptance area on the sample 18 Evacuate the chamber to a pressure of below 10 Pa 107 mbar and bake out see section 4 6 Baking Out on page 43 19 Check the vacuum before and after bakeout 20 Connect the analyzer as described in the analyzer manual Figure 2 Connec tion Scheme page 7 21 Before operating the analyzer wait for complete cool down good thermal insu lation inside the analyzer leads to a complete cool down time of about 2 3 days at least 2 days cool down is recommended 4 6 Baking Out The vacuum chamber has to be baked out to get good UHV in a reasonable time The temperature during the bake can be up to 200 C A reference thermocouple for the temperature measurement should be attached to the detector flange figure 24 Thermocouple here Figure 24 Detector Flange Before baking out e Switch off the HSA3500 control unit e The analyzer box fixed at the lens housing see figure 4 should be removed as well as e the detector box preamplifier with connection cables Channel HV Channel Base CAN 43 Installation 44 SPECS
28. Installation Introduction Troubleshooting Checks and Settings The SPECS PHOIBOS hemispherical electrostatic energy analyzer allows recording of en ergy spectra for negative particles electrons and positive particles ions in the kinetic energy range from 0 eV to 3 5 keV The PHOIBOS series of hemispherical analyzers are hemispherical deflectors available in two sizes 100mm or 150 mm mean radii The input lens is designed to accommodate a wide range of applications The analyzer can be equipped with single channel and optional multichannel detectors a 5 channel detector for the PHOIBOS 100 and a 9 channel detector for the PHOIBOS 150 The detection electronics incorporates a discriminator preamplifier counter and Introduction S P E C S R bus interface All parts are integrated into a single compact RF shielded aluminum case The detection electronics are supplied together with the analyzer control unit PHOIBOS analyzers provide the detection of electron and ion energies between 0 and 3500 eV with minimum step widths of 7 meV For ultra high energy resolution applica tions the unit can be operated in a 400 V or a 40 V range with extremely low ripple Step widths down to 80pV are possible in the lowest voltage range A multi element two stage transfer lens can be operated in several different modes for angular and spatially resolved studies All lens modes can be set electronically A Slit Or bit mechanism and a Multi Mode Lens
29. Point Transmission Mode ssssssssssessseeseseneen nennen nnne nnne nnns nnne nnns entes nnns 13 CeOmngsc aubne HR E 14 High Magnification Mode cesccccsceceececeeeeeeeeeeeneeceneeseaeeceaeeseaeeseaeeseaeeseaeeseaeessaeesaaaeeeessenaneess 15 Typical Intensity Position Profile with Iris Aperture cccccccceececeeceeeeeeeeeeeeeseeeeeneeteeeeeeeees 17 PHOIBOS Metal Shielding sessssessessssseseeseseseee nennen nennen nnn nnn nennen nnn nnns 21 Magnetic Field of the Trim Coil sess nennen nennen nnns 22 External Rotary Dial for Positioning nennen nennen nnne nnne 24 Entrance and Exit Slit Rings Slit Combination 4 B eeessesseseeeeeeeeeeeen nnns 24 i Exit Shit Tae 25 Detector Sweep Count rate vs Voltage sssssssssssseseeeeeeee nnne enne nennen nnn 29 Lifetime of the Extended Dynamic Range CEM sssssssssseeeeeeneeen nennen 30 Linearity Plot for the new Extended Range CEM ssssssssssseeeeeeneeeneeen nennen 31 Efficiency Plot for the new Extended Range CEM ssssssseseeeeeeenennen nnns 32 Detection Efficiency for Electrons and lons sssssssssssssseseseeeeeenen enne nennen nnns 33 Energy Scheme Photoelectron Spectroscopy esssesseseseeeeeeeennenenn nene 34 Removal of the Transportation Locks
30. agnification Ekint pan cein atep HighPointT ransmission 355 0 5 4 Optimize the excitation source with typical sample current of less than 1 pA Select the FixedEnergies Analyzer Mode and choose a kinetic energy with measurable counts to maximize intensity with the source deflection tools Check the function with an overview spectra PHOIBOS PHOIBOS SPECS Chapter Troubleshooting In the section Possible Problems below a list of possible problems or anomalies and suggestions for their removal is given It is assumed that the system was calibrated properly and was working according to specifications before one of the following prob lems occurred Problems immediately after installation are mostly due to short circuits caused by vibrations inside the analyzer while in transport and may be easily detected by resistance measurements section 6 1 Short Circuits on page 51 Please also note the test described in chapter 8 Analyzer Checks some spectra as well as the meas ured voltages for diagnostic purposes 6 1 Short Circuits Check the resistance of the pins on the HSA 12 pin figure 33 page 72 and detector figure 34 page 73 feedthroughs to ground and to each other to rule out short cir cuits It is especially important to check for a short circuit between the ground plate and the cathode The resistivity has to be infinite for all cases except between the cath ode and anode contacts of the CEM
31. aks are shifted Check has voltages gt section 8 4 zero point drift of the spectrometer check zero point of HSA3500 section 53 Troubleshooting 54 voltage SPECS Table 8 Peaks Shifted Equally possible cause perform check test or troubleshooting proced ure no gt incorrect amplification factor check Uo HSA3500 gt section 8 2 section 8 1 section Table 9 Peaks Shifted Differently possible cause perform check test or troubleshooting proced ure no gt malfunction of counter board section 9 1 2 one lens electrode not connected Run a spectrum with high speed Perform a crosstalk test with all lens tubes gt section 8 4 2 malfunction of the energy sweep generator check the energy sweep section section Table 10 Intensity Fluctuations possible cause perform check test or troubleshooting procedure no gt field emission at the exit slit of the HSA Background signal independent of Ekin with DE const rises with small Epass values and increases in DE E const mode Remove wir eedge from the mesh at the exit slit sparks at the anode side of the CEM background signal is independent of Ekin in DE E const mode and background to signal ratio decreases with increasing of the pass energy incorrect detector preamplifier threshold gt section 9 1 1 dark current at the isolation part
32. alysis the iris aperture may be used to sharpen up the analysis area The optimum settings for the iris aperture depends on the slit size and the desired qual ity of the analysis area The intensity position function for the analyzer is a Gaussian like function but with higher intensities in the tail regions see figure 9 Using the iris aperture these intensities can be suppressed The analysis area was defined to include typically between 90 9996 of the total photoelectron signal PHOIBOS SPECS The Lens System Slit Size Iris Diameter 7 x 20 mm 30 40 mm OT 20 30 mm O3 10 20 mm 1 2 5 10 mm Table 3 Recommended Iris Values for Spatially Resolved Measurements intensity postion x position y e os High Magnification slit 1mm lris 50 mm lris 10mm Iris 5 mm AES images using a PHOIBOS100 sample tilted Simulation Figure 9 Typical Intensity Position Profile with Iris Aperture The low tail intensity forms a disc Its integrated intensity can achieve the same order of magnitude as the intensity in the peak Using the iris aperture these intensities can be PHOIBOS 17 Spectrometer S P E C S R 18 suppressed 3 2 Hemispherical Analyzer HSA The PHOIBOS Hemispherical Analyzer HSA with a mean radius Ro 100mm 150mm measures the energy of charged particles Charged particles entering the HSA through the entrance slit S1 are deflected into elliptical t
33. alyzer 18 High Background 54 Housing seeeeeeen 8 Intensity Fluctuations 54 Introduction 1 ISS Operation 50 L Lens System 12 lifetime 27p 30 49 Low Energy Resolution 53 Low Intensity 53 M Magnetic Coupling 21 magnetic field 20pp 52p 55 Magnetic Shielding 20 M CDi E 25 MCD Calibration 60 Multichannel Detector 25 N No Spectrum eee 52 Noisy Channel 77 Noisy Spectrum 55 P Peaks Shifted 54 Quick Start sss 47 R Replacing Channeltrons 82 S Safety 3 5 44 71 76 sample distance 40 52 SGD cee ees 25 Specification Check 67 Spectrometer 11 Spectrometer Voltage 33 Switch off certain channels 77 System Description 5 T threshold 75 Trim Coil 21 U Unpacking 37 V Vacuum Installation 41 WwW Work Function 34 working distance 12 40 42 X XPS AES UPS Operation 49 XPS on Silver
34. amic spacers contact the ground plate Hold the detector in its position and tighten the flanges together with the M8 screws PHOIBOS S PEC Gs Mounting the Detector PHOIBOS Figure 22 Corresponding Hole in the Ground Plate 4 3 Achieve the Maximum Lifetime of a Channel Elec tron Multiplier To achieve the maximum lifetime of a channel electron multiplier the rules listed below should be strictly followed e After a bakeout the analyzer needs 2 3 days to cool down If channel electron multipliers are operated at higher temperatures gt 60 C they can suffer severe damage Some channel electron multipliers will lose gain and exhibit a markedly higher detector plateau The interior parts of the PHOIBOS will cool down significantly slower than the housing It is recommended to wait for a complete cool down of the detector assembly at least 2 days Even if the ana lyzer housing is cold any internal parts on insulators may still be too hot for safe operation It is imperative that all users are aware of the issue and take the necessary precautions During first use after bake out rapid desorption of surface adsorbed gas will oc cur from the walls of the channel electron multipliers so care should be taken not to use the detector at full channel electron multiplier voltage and full in tensity within the first few hours of operation We recommend to increase the detector voltage over a period of 1 5 hours up to the recommended value
35. anode cathode potential for the channeltrons UHV UBase detector voltage UChannelBase UO conversion voltage LA LE lens potentials IH OH inner outer hemisphere T1 to T10 electrodes of the multi mode transfer lens S1 hemispherical capacitor entrance slit S2 hemispherical capacitor exit plane IH inner hemisphere OH outer hemisphere ro nominal capacitor radius 100 or 150 mm C1 to C9 discrete collection single multichannel detector 1 5 or 9 channels single channel detection SCD multi channel detection MCD PHOIBOS PHOIBOS SPECS Chapter Spectrometer The PHOIBOS spectrometer consists of a vacuum housing and four major internal com ponents which are shown in figures 3 5 All the parts must be contained within an Ul tra High Vacuum UHV environment as particles emitted from the sample surface can collide with the gas molecules changing their energy and momentum The internal components are e input lens system for receiving charged particles e 180 hemispherical analyzer HSA with 100 150 mm nominal radius for per forming spectroscopic energy measurements e detector assembly for single particle detection e Slit Orbit mechanism with an external rotary feedthrough e Iris aperture with an external rotary feedthrough The excitation source is dependent upon the technique to be used but is commonly x rays or other photons electrons or ions Before the particles pass into the hemispherica
36. ate the real center posi tion of the lens system in respect to the desired acceptance area on the sample Please contact SPECS if you see a visible offset between this two positions PHOIBOS S PAC es Alignment Note that the analyzer was adjusted to the mounting flange axis during specification 4 5 Vacuum Installation Open the transport box carefully 2 Check the shock and tilt sensors If any sensor is discolored please inform SPECS immediately and await further instructions Check the sensors 1 Box outside tilt 2 Box outside upright 3 Box inside outside shock sensor outfit may differ from the pictures w Remove the shipping frame 4 Carefully lift the analyzer out of the box Be aware of outstanding parts while pulling out the analyzer In particular the rotary feedthroughs are sensitive to physical jostling bumping vibrations Because of the analyzer weight of 65 PHOIBOS100 95 kg PHOIBOS150 PHOIBOS 41 Installation 42 Specs recommends using a hydraulic lift as in the photo to the right SPA CS When mounting vertically use the hooks as shown in the picture above Never When mounting horizontally use the use these for mounting hooks as shown in the picture above horizontally Figure 23 Mounting Tips 10 11 Keep the analyzer in a stable position if possible keep the same orientation as in the transport box soft lie down is allowed
37. ation FWHMttotal is sometimes specified recording the Si 2p3 level instead of the Ag 3ds level which res ults in smaller values of FWHMextreme due to the narrower inherent line width of the Si 2p level The integral signal intensity of the measured particles the area under the peak with a background subtracted is proportional to product of the accepted solid angle Qs the accepted sample area A and the HSA resolution AE 2 u E pass x E pass I AE Q As AE p QUA ER E 9 E kin E kin where Q and A are the values of the acceptances for the HSA They are analyzer con stants The equation results from Liouville s theorem The analyzer can be operated in two different modes a Fixed Retarding Ratio FRR the retardation ratio R is defined as 1 For more information there are some excellent publications on analyzers We recommend two of them K D Sevier Low Energy Electron Spectrometry Wiley Interscience 1972 D Roy and D Tremblay Design of Electron Spectrometers Rep Prog Phys 53 1621 1674 1990 PHOIBOS 19 Spectrometer S P E C S R 20 E R 10 pass In this mode all particles are decelerated with this same fixed factor Therefore the pass energy is proportional to the kinetic energy The intensity increases with kinetic energy I E 11 while the energy resolution decreases b Fixed Analyzer Transmission FAT Epass and AEan in equation 5 are adjustable constants The signal
38. ation is changed electrically by connecting appropriate voltages to the lens electrodes The voltages are a function of the spectrometer voltage Uo which is nominally equal to Ekin Epass workfunction Ekin is negative for electrons and positive for ions The PHOIBOS system can operate in a Fixed Retarding Ratio FRR or in a Fixed Analyzer Transmission FAT mode In FAT mode the applied voltage to the hemispheres is defined by equation 3 on page 18 In the FRR mode the pass energy is given by Epass Ekin R with the retardation ratio R The actual size of the analyzer sampling area DS is in principle given by equation 1 However due to spherical aberration of the input lens the image in the plane of the entrance slit is diffused The degree of diffusion increases for a fixed magnification with the input lens acceptance angle This means that the observed area in the focal planes of the input lens system is smeared out with increasing angle resulting in larger sampling dimensions than given by equation 1 Thus the lens acceptance angle is select able by the magnification modes keeping the spherical aberration at a well known ac ceptable value A second reason for confining lens acceptance angles are angle resolved measurements e g in tilt experiments or angle resolved photoemission investigations Confining the lens acceptance angle is also essential in ISS as the kinetic energy in ISS depends on the scattering angle and thus peak b
39. be calculated N N N IN X 1 N T A 22 Extended dynamic range CEM a a N N 1 NT e Measured a 8 m a Measured count rate N cps Q 1065 16 10 10 10 10 10 True count rate N cps 10 10 Figure 17 Linearity Plot for the new Extended Range CEM The count rate N was measured for different beam currents From the low count rate region the conversion factor c N cx I can be calculated PHOIBOS 31 Spectrometer 32 SPECS Extended Dynamic Range CEM 0 Maximum count rate N max 16 8 Mcps f 2 T z S z gt o c E d iS Ww e DS o 8 B dU ee 18 Measured count rate N Mcps Figure 18 Efficiency Plot for the new Extended Range CEM From a spectral ratio plot of two spectra measured at different beam currents the de tector efficiency N N was calculated With increasing count rate the mean gain of the pulse height distribution will decrease For some critical value the distribution starts to fall below the discriminator threshold Conclusions The maximum measured count rate detectable is 5 6 Mcps per channel for the standard CEMs and 16 8 Mcps for the extended range CEMs The linearity and the non extended dead time behavior for the standard CEMs up to 1 Mcps and for the extended range CEMs up to 10 Mcps true count rate is verified Up to these count rates no significant deviation from linearity could be observed with the PHOIBOS detection sys
40. bout 85 mA or 85 mA to compensate the residual magnetic field within the hemispheres To find the optimal value for the current the signal measured by the analyzer at low pass energies lt 10 eV should be maximized by changing the coil current If the analyz er is equipped with a coil short circuit of PIN 12 to ground of the analyzer feed through and the power supply HSA 3500 is equipped with a current module the con trol software allows the setting of the coil current In all programs the coil current set ting can be found in the analyzer settings menu as an additional field 3 4 Slit Orbit Mechanism The slit orbit mechanism is used to manually change the entrance and exit apertures of the analyzer The mechanism positions an entrance and exit opening of the appropriate size in the analyzer entrance and exit plane The entrance beam is defined by a pair of slits which are about 6 mm apart The posterior slit lies in the entrance plane and defines the analyzer energy resolution see equation 5 on page 18 while the anterior slit serves to match the angular spread for the analyzer For a given energy resolution and a given tolerated analysis area and acceptance angle the largest possible slit PHOIBOS PHOIBOS should be selected This enables the highest possible count rate for these parameters and thereby a short measurement time and a good signal to noise ratio The entrance ring can be positioned directly by rotating the dial s
41. cccccsssseeessssneeeeecssnneeeessssseeeeesssneeeees 67 8 3 1 Survey Spectrum of Silver esesesessseseeseeeeenn nennen 67 8 3 2 Intensity and Resolution 2 nid ECce eerie pr iecore haan dubia rU DUC 68 8 4 Connection Check of the Analyzer Electrodes 70 8 4 1 Capacitance Check for El ctrodes cccccccsccecsssseeessseeessseeeesssssssanseeeess 71 8 4 2 Check the Cable COntacts cccccsssssssseceeeeeeeeeeseeeeesssseceseneeseeeeeaseeeeeees 71 8 5 Check all analyzer voltages eese 73 PHOIBOS PHOIBOS SP CS 9 Deflector Settings 9 1 Preamplifier 9 1 1 Discriminator 91 2 Amplifier Check 9 2 Detector Voltage 9 3 Noise eee 9 3 1 Suppress a Noisy Channel 9 3 2 Switch off Certain Channels 9 3 2 1 Mask example for MCD9 9 3 2 2 Mask example for MCD5 10 Spare Parts 10 1 Cu Gasket 10 2 Multiplier 10 2 1 Channeltron Handling and Storage 10 2 1 1 Handling of the Multiplier 10 2 1 2 Operation of the Multiplier 10 2 1 3 Storage of the Multiplier 10 2 2 Change a Channeltron 10 2 2 1 Removing the Detector Flange 10 2 2 2 Replacing Channeltrons 10 2 2 3 Mounting the Detector Flange Table of Contents Table of Contents S PE C S PHOIBOS PHOIBOS SPACS Chapter Introduction 1 1 Overview Chapters in this manual Procedures Information Components and Connection Spectrometer Description
42. ctional Test on page 49 Check the electrical connections see sec tion 4 7 Electronic Units Installation on page 44 After storage for a prolonged period please read the start up procedure given for the CEM after bake out in section 4 6 Check the detector voltage given in the Specification Report for your analyzer spectra prints column Udet with the default detector voltage menu Analyzer Settings A monthly check of this parameter see figure 15 page 29 is recommended Quick Start Check vacuum conditions Check sample Switch on the analyzer supply HSA3500 see sec tion on page Start the acquisition program SpecsLab2 Select the HSA3500 control unit in the menu Ana lyzer Settings Switch on the excitation source Choose the desired slit combination table 4 on page 23 A typical slit combination for standard XPS and large samples 10x10mm is 2 7x20mm 2 open Set the Iris aperture to the desired diameter Set the scan parameter for the region e g figure 31 page 68 Press Validate and then Measure window Region Edit Save the results Switch off the units Analyzer Settings x r amp nalyzer Server Phoibos Hsa3600 X none 1 Name Phoibos Hsa3000 Phoibos Hsa3500 Detector fall Settings r Sources Method PS Y Server oe we Name r Remote Server none m Name 47 Unit Operation S P E C S 8 48 5 3 Detailed O
43. de Analysis Mode ves 1 05 IEE LargsArea Dstectorvaltage5can Eexc Ekin Epass F Ubias I Udet Start T we o fi oo fi a 90 a5 Ekin Epass Udet Step Udet End Values Scans Dwell Time Comment Default Values Detector starting up within 10min after bakeout Load ig Save Previous Next Mew Validate Sar Figure 25 Starting up the detector Operating conditions e A dry pumped or well trapped diffusion pumped operating environment is de sirable A poor vacuum environment can shorten CEM life or change the operat ing characteristics e A pressure of 1 10 mbar or lower is preferred Higher pressure can result in high background noise due to ion feedback e Voltage should be applied to the MCD in small 100 200 V steps PHOIBOS S PEC Ge Detailed Operation PHOIBOS e For optimal lifetime operate the detector at the minimum voltage necessary to obtain an usable signal see section 3 5 3 Electron Multiplication on page 27 e Microchannel plates and Channeltron detectors can be degraded by exposure to various types of hydrocarbon materials which raise the work function of the sur face causing gain degradation e f channeltrons are operated at higher temperatures gt 340 K they can suffer damage Some channeltrons will lose gain and exhibit a markedly higher de tector plateau 5 3 3 Functional Test 5 3 3 1 XPS AES UPS Operation To begin the detector unit should have alrea
44. dy been baked out A silver sample with a size not smaller than 5x14 mm should have been transferred into the vacuum cham ber The sample has to be cleaned by sputtering The base pressure should be lower than 10 mbar 10 Pa to avoid a damage to the detector by sparks For special reas ons e g for depth profiling with noble gas ions operation up to 10 mbar 10 Pa is allowed Adjust the detector voltage to the value corresponding to the Specification Report of the analyzer or check the actual value see The Working Point of the CEM s on page 27 Measure a wide energy XPS spectrum scanning the kinetic energy of the particles from 200 to 1 5 keV e g with an energy step of 500meV and in FixedAnalyzerTransmission mode with pass energy of 10 20 0 eV Figure 31 XPS on Silver Wide Scan PHOIBOS 150 MCD9 page 67 Group Region Method Lens Slit Mode Scans Dwell Delta Ex Ekin Epass Ubias Udet 300W Overview XPS MA 2 7x20 FAT 1 0 01 0 3 1253 6 200 1267 4 13 90 1950 300W MA13 2 open In a first rough test without careful adjustment one should get few 10 cps at the Ag 3d5 2 peak using 100 W Mg Ka X ray source power If not check the photoemission sample current which should be in the range of 25 40 nA for 100 W Mg Ka Secondly check the MCD voltage and the discriminator level of the MCD preamplifier Also check whether the intensity of the C
45. e packaging until it can be bolted directly onto the system Take great care when unpacking to prevent damage Do not rest the analyzer on the ceramic feedthroughs lens or the viewport Handle parts on the vacu um side of the flange seals using normal UHV protection i e wear gloves and use clean nonmagnetic tools The analyzer is evacuated In order to avoid any damage modest vacuum conditions 10 mbar have to be maintained Please check vacuum conditions every three months when storing the analyzer Please note the parts list in section 2 1 System Description Package Contents on page 5 4 2 Mounting the Detector Caution Remove the three transportation locks before mounting the detector 37 Installation SPECS 38 Figure 21 Removal of the Transportation Locks Release the four M8 screws vent the detector with Nz and pull it carefully out of the storage housing If one looks into the opened detector flange of the analyzer from the bottom side you can locate the alignment hole for the detector Align the pin at the top of the detector assembly with the corresponding hole in the ground plate see fig ure 21 Be sure that the detector is nearly parallel to the ground plate and push the de tector carefully into its seat While pressing the detector into its seat make sure that the distance between the two flanges is approx 4 mm before you feel that the springs are compressing This will ensure that the cer
46. eck that the values are correct if you display the single channels and compare the energy position of each channel Second compare two different pass ener gies Large differences suggest the need to calibrate this lens slit combination as de scribed below 1 Identify a single high intensity peak in your data and set up a region that only measures this peak 2 Open a separate group with identical regions except pass energy for a single peak within the region e g pass energies 10 20 30eV LI ETE Sa Ed Ve indem oit peters Ween Hep amp s SHES POR Moe S Ser e JI EIE FIER EL IC fi 1 2 alal sil a 5 0e6u0x v EB PHOIBOS 180M4CD Sano 36834 V Inbareaty 105 Cp boty Figure 28 MCD Calibration 3 Measure the regions 4 Select the tool MCD Calibration in the Tool menu 5 Calculate the Ek shift Ep by pressing Calculate button PHOIBOS PHOIBOS 6 Check to see if the differences and the peak MCD Calibration x position are reasonable If the calculation s Pass Energies 1 V HH Spezifikation 30 01 2002 j 88 1320 failed check that the peak position can be bs SuSE calculated for all regions Mostly regions nus rasana I Medium rea O 1 0 5 2032 openn with low count rates low pass energies fail D komanan O a70 Move this region into another group and try Ekara Darasa again Drag and drop of the region via B eserores el fl UIS m
47. ee figure 13 En trance and exit slit rings slit combination 4 B page 24 The exit ring on the other hand is positioned indirectly by the use of the entrance ring see Figure 13 Entrance and Exit Slit Rings Slit Combination 4 B page 24 Through this arrangement one can choose the entrance and exit slits independently using the same rotary drive The PHOIBOS analyzers beginning with release 5 have 8 entrance and either 2 exit slits in the standard configuration or 3 upon request The entrance slit positions are indic ated by numbers 1 8 on the external rotary dial see Figure 12 External Rotary Dial for Positioning page 24 The exit slit positions are indicated by letters A B or A B and C These indicators correspond to those which appear in the region settings of the analyz er control software SpecsLab 2 Whenever the entrance and exit aperture is changed the positions must be entered in the region edit dialog The arrangement of the slits may be other than those shown in table 4 on page 23 The actual arrangement present in an analyzer appears in the slit selection dialog of the control software delivered with the analyzer Entrance S1 Exit E2 Slit Number Slit Size Slit Number Slit Size 1 0 2 x 20 mm Free choice of A 0 25 x 20 mm 2 0 5 x 20 mm each slit combination 3 1 x 20 mm 4 3 x 20 mm B Open for CEM each 5 7x20mm except channel is 7x21 mm 6 dia 1 mm mcm C 3 x 20 mm 7 dia 3 m
48. epends on pass energy perform the MCD Calib ration see section 7 3 page 60 If the calibration does not fix the problem and or there is a strong dependence please refer to section on page Short circuits or sup ply failure can cause such behavior After voltage check please contact SPECS and send some spectra as well as the measured voltages to help diagnosis of the exact problem Note that there is a weak dependence of the peak energy on beam position at the sample and the size of the illuminated area Because SPECS calibrates the analyzer with 65 Analyzer Checks S P E C S R a broad illuminating X ray source additional MCD Calibration for the point source may be required 8 2 Energy Scale Tests with XPS 8 2 1 Check Kinetic Energy Scale Transfer a gold copper sample into the system Clean carefully by ion sputtering With this sample the main peaks are separated far enough for calibration purposes The Au 4f7 2 and Cu 2p37 peaks energy difference is 848 66 0 03 eV Adjustments Excitation Mg Ka X ray power 100 W Slit entrance largest slit exit open Mode Medium Area Binding energy range 82 86 eV for the Au 4f7 2 peak 930 937 eV for the Cu 2p3 2 peak Dwell Time 100 msec Scan 1 Energy step 25 30 meV Pass energy 8 eV 8 2 2 Check Peak Position Check for proper peak positions corresponding to table 14 on page 67 If the peaks off set consistently check if the proper peak position can be achieved
49. experiment chamber is also neces sary and to facilitate magnetic coupling to these parts the PHOIBOS analyzer is de livered with a collar attached to the front of the lens shielding The chamber shielding needs good physical connection to the analyzer shielding especially for slowly charged particles The insertion depth of the analyzer shielding has to be modified if the shield ing is too far inside the chamber normally by a non magnetic lens protection cap ad ded to the lens shielding Please contact SPECS for advice regarding the metal shield ing 3 3 2 Trim Coil The PHOIBOS analyzer can be equipped with a trim coil around the outer hemisphere of the analyzer With a coil current Icoil lt 150 mA the residual magnetic field compon ent within the analyzer along the lens axis can be compensated The magnitude and the sign of the coil current depends on local terms The radius of gyration G for an electron with kinetic energy E in a magnetic field B is VE mnl eV B uT RG m 3 37 14 At the center of a very short coil with coil current I radius R and n windings the mag netic field is 21 Spectrometer S P E C S R 22 B uy 15 Current How i Figure 11 Magnetic Field of the Trim Coil For the PHOIBOS 150 analyzer B pT 0 017 x I mA and for the PHOIBOS 100 analyzer B T 0 026 x I mA In the case of an earth magnetic field of about 50 uT with the lens axis nearly parallel to the field one needs a
50. for a PHOIBOS PHOIBOS S PEC e Specification Check PHOIBOS The signal net intensity i e peak count above background of the Ag 3d5 2 peak is about 85 200 kcps channel depending on the sample to X ray source distance The back ground in this case is defined as a straight line between the two neighbouring valleys on both sides of the peak The FWHM of the Ag 3d57 peak is calculated by measuring the peak width at the half height between the peak maximum and the background Note Because of considerable spread in the gain of different CEM s the voltage required for the signal may differ from the specifications see section 9 2 Pay attention to the de tector voltage value in the Specification Report for the analyzer Monitor the aging of the channeltrons monthly and adjust the default detector voltage If the measured spectra and values differ substantially from those in the Specification Report of the analyzer it may be necessary to sputter the sample again or optimize the sample and X ray source positions or a HSA 3500 calibration might be needed Oxida tion of the anode material may also lead to peak broadening In many cases it is helpful to know the intensities signals and accompanying FWHMs at different pass energies The measurements described above should be made at pass en ergies e g of 2 5 10 20 and 50eV for largest slit and up to 200 eV for the 1mm slit dia meter The Dwell Time or number of scans should be adapted
51. g Ka Xc rays susssse 67 Table 15 Capacitance Measurements pF PHOIBOS100 R6 or higher ssesssseeeeeee 71 Table 16 Capacitance Measurements pF PHOIBOS150 R6 or higher sssssssseeeeeeeeee 71 PHOIBOS V Chapter A Amplifier Check 3 14 16 23 27p 30 35 37 43p 47pp 55 58pp 65p 70p 77 Analyzer Alignment 40 Analyzer Checks 65 Analyzer Feedthrough 22 72 B Baking Out 43 C Cable Contacts 71 Calibration sss 57 Capacitance Measurements 71 CEIVE Lotte tee ea 27 Change a Channeltron 82 Channeltron Handling 81 Check Peak Position 66 Coherence of Epass and Step 26 Eo esee 21 coil CUEN srianan 21 Connection Check 70 Connection Scheme 7 conversion voltage 33 current module 22 D DAC Precision 59 Detector Feedthrough 73 Detector Sweep 29 Detector Voltage 76 E Electrical Connections 6 PHOIBOS SPECS Index Electron Multiplication 27 EXC SM e n 24 Extended CEM 29 F First Operation 47 Functional Test 49 H Hemispherical An
52. haracteristics of these devices 10 2 1 3 Storage of the Multiplier Due to the hygroscopic nature of the doped lead glass it is important that the channel trons are stored properly Warning The shipping containers are not suitable for storage periods exceeding the delivery time Upon delivery to the customer s facility channeltrons must be transferred to a suitable long term storage medium e The most effective long term storage condition for the channeltron is a clean oil free vacuum e A dry box which utilizes an inert gas such as argon or nitrogen heated above the dew point is also suitable e Desiccator cabinets that utilize silica gel or other solid desiccants to remove moisture have been proven to be unacceptable 10 2 2 Change a Channeltron A multiplier loses its gain with operating time It should be changed when a significant degradation in amplification i e intensity is experienced or the detector voltage limit of the control unit is reached 10 2 2 1 Removing the Detector Flange Switch off the analyzer supply Remove both the detector and analyzer connections Vent the system Open the detector flange let the detector unit down slowly and put it carefully on a table Three springs pressing the detector assembly to the groundplate may exert some force downward when the screws are released 10 2 2 2 Replacing Channeltrons e Note Use dry nitrogen only in order to remove dust or lint e Loosen the three
53. he PHOIBOS analyzer consists of the following internal parts analyzer housing internal pi metal shielding lens system hemispherical analyzer multichannel MCD or single detector SCD Slit Orbit mechanism e HSA3500 power supply for PHOIBOS analyzer fully remote controlled e andthe following additional parts Mounting instructions Manual Safety Instructions Manual PHOIBOS Manual SpecsLab2 Manual CasaXPS Second network card Fast Ethernet PCI Adaptor Detector electronics PCU 300 Handle for power supply HSA3500 2 x RS232 cables CAN bus cable 10 Pair of DN100CF copper gaskets 11 Cross over cable 2m 12 Ethernet cable TP 2m 13 2x terminator plugs CAN bus 14 Power line cables 15 EC10 CAN Ethernet Adapter section on page 16 Magnet holder for EC10 Adapter 17 Vacuum interlock plug shorten pin1 pin2 18 HSA3500 cabinet feet CON AM PWN PHOIBOS Components and Connections S P E C S amp Analyzer box with filter unit cube or cylinder shape fixed cable SHV cable ChannelBase SHV cable ChannelHV SpecsLab2 Installation CD Specification Test Report Pair of DNAOCF copper gaskets Pair of DN16CF copper gaskets Two Lugs for analyzer lift Two Lugs for analyzer support only PHOIBOS 150 Screws for lens flange screws and nuts for PHOIBOS 100 and bolts and nuts for PHOIBOS 150 HSA3500 Figure 1 Package Contents 2 2 Electrical Connections The electrical con
54. he detector assembly figure 39 Align the pin with the hole in the ground plate Be sure that the detector is nearly parallel to the ground plate and push the detector carefully into its seat ALIGNMENT PIN Figure 39 Alignment Pin Pump down Detector must be baked out at a vacuum pressure lower than 1 105 mbar It is bakeable up to 200 C Check the detector according to section 8 3 see Figure 15 Detector Sweep Count rate vs Voltage page 29 checking the single channels in the acquisition software may be enough PHOIBOS Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure 24 Figure 25 Figure 26 Figure 27 Figure 28 Figure 29 Figure 30 Figure 31 Figure 32 Figure 33 Figure 34 Figure 35 Figure 36 Figure 37 Figure 38 PHOIBOS SPECS Chapter L F List of Figures PACKAGES COnteNtS irinenn ndee nena DL LLLI 6 Connection Scheme x rn ke E E Ero a a Aaa ERE RE eaa AEUR Raes 7 Analyzer Housing PHOIBOS100 ssesssssssseseseeee eene enne nennen nnne nennen nnn nnns nne 8 Analyzer Housing PHOIBOS150 ssssssssssseseseeeee nennen emen nnne nennen nnn nnn nnns sss 9 Analyzer Main Components and Voltage Principle seesesesssseeeeeeerne 10 High
55. he detector consists of the following parts e an arrangement of Channel Electron Multipliers CEMs 1 for SCD 5 or 9 for MCD consisting of discrete collectors specially screened against external HF sig nals for maximum noise rejection e a multi pin ceramic high voltage vacuum feedthrough specially designed for low cross talk e SCD MCD preamplifier 3 5 1 Principles of Detection Due to the spherical symmetry of the HSA a one to one image of the circularly shaped entrance slit with a radius of curvature Ro exists in the exit plane for monochromatic electrons with a nominal pass energy Epas The images of electrons possessing different energies within the HSA are concentric circles In a first order approximation the radial image position R for electrons with kinetic energy E is given by R R EE pass D R R 0 pass 0 16 where D is the has dispersion The theoretical value for D is 25 Spectrometer S P E C S R 26 D 2 R 17 The experimentally determined dispersion value can be slightly different mainly due to fringing fields at the edges of the analyzer Multichannel detection is performed by appropriately arranging 5 or 9 CEM s as collect ors with 5 or 9 exit slits on concentric circles in the exit plane The radial distance between neighbouring exit slits AR is selected to meet the requirement of a constant kinetic energy difference between neighbouring channels AE The number of particles N arriving
56. ions are e inherent line width of the atomic level AElevel e g O 1s C 1s PHOIBOS S PEC Ge Hemispherical Analyzer HSA e natural line width of the characteristic radiation used for excitation AEphoto e g Mg Ka AI Ko The observed total FWHMtotal is given by the convolution of the single FWHMs e g for gaussian line widths FWHM 47 AEL A E pat A E poto P AE 6 photo FWHMtotal is usually specified using a sputter cleaned silver sample and recording the Ag 3d5 2 level after linear background subtraction For Mg Ka excitation the resolution at low HSA pass energies for the Ag 3d5 2 level is found to be HM 0 8 eV 7 Mg K In most practical work a resolution of 0 9 eV is usually sufficient for high resolution in vestigations For higher instrumental resolution it is possible to use monochromatized X radiation for excitation e g mainly monochromatized Al Ka radiation For mono chromatized Al Ka radiation and for the Ag 3d5 2 level the extreme resolution is found to be FWHM 0 44eV 8 extreme To obtain the extreme resolution of 0 44 eV the FWHM of the X ray has to be heavily restricted by utilizing only a small part of the X ray monochromator spot area due to the energy dispersion across the spot area at the expense of a strong loss in intensity In practice a resolution of 0 65 eV is usually sufficient for high resolution investigations with monochromatized Al Ka excitation For monochromatic radi
57. ix Badago s r Exe e aR eA dl oe num x o AB PHAROS 150MCD SARANDI h id EF 530 moll PAHM 0 1 BABA cV 12 D s O05 Bing Energy j e Figure 29 Fermi Edge Operation Note the advice given in section 7 2 Recalibrate the DAC Precision on page 59 For more detailed information please contact SPECS support 7 5 Work Function Calibration with XPS Please note the comments given in section 3 6 Work Function on page 34 and in the description in section 7 4 Instead of the UV excitation section 7 4 X ray excitation is used to calibrate the Work Function Note that you have to select at least the 1500V range see SpecsLab2 menu Analyzer Settings in case of Mg Al Kalpha excitation This voltage ranges has a lower accuracy than the 40V range on page 7 6 Offset Calibration with UPS UV excitation recommended Please note the comments given in the paragraph Work Function on page 35 and the comments given in section 7 4 Thermal or other effects can change the accuracy of the offset and gain over time This can be compensated for with the software The values for the energy ranges can be changed separately in the Menu Analyzer Settings see Figure 26 The procedure de scribed in Work Function Calibration with UPS on page 58 as well as section on page should be done first if there are any doubts about the supply s accuracy or the Work Function se
58. l analyzer they first pass through an electron lens system and a slit Both the electron lens system and the slits sizes entrance and exit have an effect on the energy spread detected by the analyzer The input lens system Figure 5 Analyzer Main Components and Voltage Principle page 10 includes ten lens tubes For undisturbed image quality the input lens system is grid free The lens stages define the analysis area and angular acceptance by imaging the emitted particles onto the entrance slit of the analyzer Particles passing through the lenses are focused onto the input slit S1 and are retarded in the lens for subsequent en ergy analysis In addition the lens stages define the acceptance angles and area for a given magnification entrance slit see table 2 on page 16 The lens system may be operated in several different modes for angular and spatially resolved studies to adapt the analyzer to different tasks All lens modes can be set elec tronically For small spot analysis a lateral resolution down to 100 um is available using the High Magnification Mode and the special Iris aperture In the various Magnification Modes 11 Spectrometer S P E C S R 12 angle resolving is accomplished with an Iris aperture in the diffraction plane of the lens system using the lris the angular resolution can be continously adjusted while keeping the acceptance area on the sample constant The transmission modes are optimized for high transmissi
59. lt Bias Voltage Electrons V Default Bias Voltage lons v Default Detector Voltage V Analyzer Workfunction V Recalibrate DACs Precision gt Recalibrate DACs Precision Maximum Count Rate kcps Hardware Trigger Range Gain 3 5kV Range Offset 3 5k Range Gain 1 5kV Range ffset 1 5kVv Range Gain 400 Range ffset 400 Range Gain 40 Range Offset 40 Offset and Gain for the different modules energy ranges aeu Cancel Figure 26 Menu Analyzer Settings 7 4 Complete Calibration Procedure A complete calibration procedure consists of see Figure 27 Analyzer Cailbration Pro cedure page 59 1 Check set offset and gain with voltmeter i e the calibration of the modules via high precision voltmeter and high voltage probe section on page 2 MCD Calibration i e the estimation of the energy shifts of the single chan nels for selectable slit lens combinations see section 7 3 on page 60 which in cludes the calibration of the peak position independent of pass energy see sec tion 8 1 on page 65 If the achieved values differ substantially from the existing default values or a strong dependence on pass energy is observed for the spectra this can point out an analyzer malfunction which can not be corrected by the calibration procedure Please contact SPECS and send some spectra to assist in diagnosis 3 the estimation of the analyzer workfunction see section 7 4 on page 61
60. m and 8 dia 7 mm 1 C Table 4 Standard Slit Configuration May be different for your analyzer please check the slit selection dialog of the Spec sLab2 software 23 Spectrometer S PAC S Figure 12 External Rotary Dial for Positioning The indicators on the rotary dial are used for positioning but it must be taken into ac count that the rotary dial has some backlash The correct slit positions are defined by spring loaded indexing balls Because of the rotary feedthroughs backlash rotate it beyond the desired position until the indexing ball snaps in After positioning the dial jog it back and forth to ensure that the index is probably en gaged The correct positioning of the entrance slits can also be checked by looking through the view port In a configuration with two exit slits the positioning of the exit slit is not critical because of the end stops In configurations with a third exit opening please be aware that positioning of slit B can be tricky and require some practice An analyzer configured with two exit slits can be reconfigured on request standard x 39 mm PHOIBOS 10p Exit Slits 20 x 71 mm PHOIBOS 15 Figure 13 Entrance and Exit Slit Rings Slit Combination 4 B 24 PHOIBOS S PEC e Slit Orbit Mechanism PHOIBOS move exit slit by rotating entrance slit ring Figure 14 Exit Slit Selection 3 5 Single and Multichannel Detector SCD MCD T
61. mission at the impact on the CEM wall For electrons this is roughly in the en ergy range between 100 800 eV e Forions the yield increases with the kinetic energy roughly up to 10 keV Standard settings are e for electrons Usus 90 V e forions Uss 2000 V 3 5 5 Spectrometer Voltage U The main retardation voltage of the spectrometer UO is numerically equal to the differ ence between kinetic energy Ekin and pass energy Epass Work Function WF Be cause of the different polarity of the lens and hemisphere voltages in the different ana lyzer modes XPS AES UPS or ISS the value UO is calculated by U groundplate B E kin E pass WF q 24 The spectrometer voltage is applied on a groundplate and lens element 10 Figure 5 Analyzer Main Components and Voltage Principle page 10 and Figure 33 Schematics of the 12 pin Analyzer Feedthrough page 72 as well as the comments in section on page Example WF 4 5 eV Ekin 21000 eV Ep 100V 33 Spectrometer S P E C S 8 e for electrons Uo 895 5 V e forions Uo 895 5 V 3 6 Work Function The basic energetic properties are shown in figure 20 for the example of the measure ment of photoelectrons sample spectrometer charged particles Lamm gt E zix kin vacuum level Wf sample core levels Figure 20 Energy Scheme Photoelect
62. nalysis a lateral resolution down to 100 um is available using the High Magnification Mode and the Iris aperture The magnification modes were optimized to allow very large acceptance angles for high transmission from point sources Point Transmission Modes In these modes angu lar resolution is accomplished with the lris aperture in the diffraction plane of the lens system Using thie Iris the angular resolution can be continuously adjusted between x1 and x9 while keeping the acceptance area on the sample constant The rays close to the lens axis paraxial rays are focused at the Gaussian focus Rays entering the lens at a larger angle are converged more strongly The disc of minimum confusion is where the envelope of emergent rays has its smallest diameter Slight under focusing of the lens displaces the disk of least confusion to the image plane Thereby a higher angular acceptance is achieved but the spatial resolution is worsened This makes the Point Transmission Modes most suitable for AES ISS and synchrotron studies As with the High Magnification Modes the Iris Aperture can be used to continuously adjust the an gular acceptance PHOIBOS SPECS Radial Distance mm Radial Distance mm PHOIBOS The Lens System 30 Intermediate Plane Image Plane Analyzer Entrance Plane 15 bt es 1 Bad Ray Iris Aperture Plane 30 i i 0 100 200 300 400 500 6
63. nection diagram is shown in figure 2 page 7 The connection to the analyzer and the detector are supplied by two multi pin vacuum feedthroughs that are designed for high voltages up to 5 kV More detailed descriptions are given in section and section 8 4 All devices must be switched off before connecting or removing cables PHOIBOS Electrical Connections op s eds wwwwj diu ep soedsgioddns ew E80Z v9v OE 6p Xel 0 v78 9v 0E 6p ououd ulag SSEEL S sey oA ABojouyra 1e1nduio5 pue sis jeuy Vens HAWD S53dS p18 YIOMYSU e 0 Palp JO YAOMISU 19ul9t13 PIA uonb euuo pyepue3s uoisJ8A 403depy 0123 NYD 10jeuluJo pae yuomg pse gt puo es 310M ou 00 Nd unde aseg jauueyd sng NYD oreu E AH auueyD u aans asegjouueuD e opie1u n H Jeuueu5 jez jeuv amv Se LLLI aseg auueu gt uonesado 104 pesop aq 0 sey z uid pue uid auuel ANT A WNNLA JOY jeuiou s u uodwo SOgIOHd 24 JO aways uonp suuo SoJds Figure 2 Connection Scheme PHOIBOS Components and Connections Viewport for Aligment DN37OCF DN100CF 7 Electrical Feedthrough Additional Pumping Port DN38CF Variable Slit Drive DN100CF DN100CF rotatable Rotary Device for Iris Aperture not visible Weight approx 66 kg Dimensions in mm Figure 3 Analyzer Housing PHOIBOS 100 L40 430
64. nsity sources like electron sources needs special care Start with lowest source strength and narrow slit settings to avoid possible degradation e Measurements at the secondary electron cut off needs special care Use low pass energies 3 5 eV and small slit settings to avoid possible degradation 4 4 Alignment Non shielded chambers need no special modification of the lens protection analyzer shielding For shielded chambers the shielding needs a good physical connection to the analyzer shielding especially for slow 100eV charged particles The insertion depth of the analyzer shielding has to be modified if the shielding is too far inside the chamber nor mally by a non magnetic lens protection cap added to the lens shielding Please con tact SPECS in this case For XPS the distance between the X ray source and the sample should be minimized to obtain maximum count rates The distance between the sample and the lens T1 must be fixed to the working distance sample distance of 40 mm see also section 4 4 Align ment on page 40 None of these three parts should be in physical contact with one another The performance of the channeltron decreases with time when exposed to air Try to minimize the time between its installation and evacuation the system 4 4 1 Analyzer Alignment After mounting the analyzer on the chamber a check of the sample positioning via the analyzer viewport should be done Use the iris aperture to loc
65. on at different spot sizes of the source The lateral resolution is worsened and the acceptance area normally not defined by the lens In the angular dispersive modes the emission angle distribution is imaged instead of the real image All lateral resolution is lost but instead the emission angle information is easily available These modes are intended for UPS band mapping Fermi surface map ping or similar experiments In the hemispherical capacitor the particles passing through the entrance slit S1 are fo cused onto the capacitor output plane S2 The radial position of the slit image in plane S2 depends on the kinetic energy of the particles in the capacitor Particles on the cent ral trajectory possess the nominal pass energy They are focused to the central radial position at the exit plane S2 Particles with higher kinetic energy are focused further outside and particles with lower energy are focused further inside in plane S2 This of fers the possibility of multichannel detection with simultaneous recording of an energy band around the nominal pass energy Particles passing through the capacitor output plane S2 are accelerated onto the detector system C With the multichannel detector each channel is connected to a separate preamplifier mounted outside the vacuum The preamplifiers are read out by the Multi Channel Detector MCD counter interface of the SPECS data acquisition software 3 1 The Lens System The multi element two s
66. ouse in the Files window If you want to Q check which region is causing the problems Cee AE PT test that each single channel for the region are able to perform the calculation switch off noisy wrong channels of the re gion and check if the peak location with Tools Peak Location work if work also MCD calibration will work 7 Pressing the apply button will apply the calculated shifts to all chosen slit com bination The default values registry entries will be overwritten 0 10506 0 00045 A 0 07791 0 00042 0 05121 0 00051 0 02422 0 0004 0 00258 0 0005 0 02774 0 0004 7 4 Work Function Calibration with UPS UV excitation recommended Please note the comments given in the section 3 6 Work Function on page 34 Thermal aging or other effects can change the coating of the analyzer and therefore the workfunction over time Grounding the sample and the power supply influence the work function as well The default workfunction value can be corrected in the software in the Menu Analyzer Settings see Figure 26 If you are in doubt about the accuracy of the power supply it is recommended to perform the test calibration described in section on page first Note the voltage range used while measuring 40V 400V 1500V or 3500V see SpecsLab2 menu Analyzer Settings 1 Warm up the HSA3500 at least 10min Switch off and on again to reboot and force a startup calibration or
67. peration 5 3 1 Slit Setting There are different settings available with the PHOIBOS Slit Orbit mechanism To under stand the possible slit combination for this analyzer please see section 3 4 Slit Orbit Mechanism on page 22 The optimum setting is reached when entrance slits are aligned along the lens axis i e when the particle number passing through the lens stages and impinging on the hemi spherical capacitor entrance slit S1 is a maximum There is also the correct position for the exit slit S2 Usually there are only two exit slits therefore physical stops in both dir ections means that this is also the correct exit slit position In positioning the feed through Figure 12 External Rotary Dial for Positioning page 24 to the slit locations the rotary dial is internally fixed near to the right value by a physical rest position Please check the marking at the rotary for the desired combination Additionally a check via the viewport for alignment may help A typical slit combination for standard XPS and large samples 10x10mm is 2 7x20mm 2 open 5 3 2 Detector Operation For new multiplier CEM please read the start up procedure given for the CEM after bake out in section 4 6 The normal procedure after bake out is increasing the detector voltages in small steps 100V over a period of 10 min without excitation Region Edit Biel Es Name Group Analyzer Acquisition Date Region Group Method Entrance and Exit Slit Lens Ma
68. pical accuracy of the energy scale depends on the voltage range used Table on page For the 40V range the accuracy is about 3 meV and for the 3500V range about 100 mV without re calibration The drifts are due to different temperatures during cal ibration at the factory and work in the lab Also the workfunction of the analyzer can change due to bakeouts with recalibration the accuracy of the energy scale can be sig nificantly improved table on page If energy shifts of well known peaks occur check the grounding of your sample There should be no potential difference between the ground of the sample and the ground of the power supply Next check the accuracy of the high voltage ranges 40V 400V with a high precision digital voltmeter and the voltage ranges 1500V 3500V with an additional high voltage probe 1000 1 section on page To recalibrate the unit please follow the procedures in figure 27 page 59 Please note the parameters of the modules given in the table on page in section A description to select a default detector voltage is giv en in section 9 2 on page 76 and the meaning of the threshold for the preamplifiers is described in section 9 1 1 on page 75 57 Calibration Analyzer Settings x XPS Voltage Range V Range 1500V m desired voltage range 9 j UPS Voltage Range V Rams v el AES Voltage Range V Rane 30y m 185 Voltage Ranae V Range 500V Defau
69. rajectories by the radial electrical field between the inner hemisphere Ry and the outer hemisphere Rour The radii of the PHOIBOS hemispheres are 1 25 Ro and 0 75 Ro respectively The entrance slit S1 and exit plane S2 are centered on the mean radius Ro R mer tR Re 2 150mm 2 For a fixed electrical field gradient only particles with kinetic energies in a certain en ergy interval are able to pass through the full deflection angle from the entrance slit S1 to the exit plane S2 Particles with higher kinetic energy approach the outer hemi sphere whereas particles with lower kinetic energy are deflected toward the inner hemisphere Those particles which enter the HSA normal to S1 and move through the hemispheres on the central circular trajectory have the nominal pass energy Epass E pas 4 kVV 3 where q is the charge of the particle AV is the potential difference Vout Vin applied to the hemispheres k is the calibration constant R inner R out RR R O 4 inner k These particles reach S2 at the nominal radial position Ro If the HSA accepts the half angle a in the dispersion direction the HSA resolution or FWHM full width at half max imum of the transmitted line AEan is given by AE 5 a E 2R 4 6 pass 0 where S S S2 2 This value is a constant of the analyzer There are additional contributions to the line width observed in the spectrum For photo emission lines the main additional contribut
70. roadening or double peaks appear when the lens ac ceptance angles are too large 30 Reiarding Ratio b Intermediate Plane 15 gt E Sample o 2 S 0 Analyzer E Entrance Plane Es 8 Disc of Least a5 Confusion Iris Aperture Plane 30 i f 0 200 400 600 Longitudinal Distance mm Figure 6 High Point Transmission Mode 13 Spectrometer S P E C S 8 14 30 Retarding Ratio 10 Intermediate Plane Analyzer Entrance Plane Radial Distance mm Iris Aperture Plane 0 200 400 600 Longitudinal Distance mm Figure 7 Medium Area Mode High Magnification is see Figure 8 High Magnification Mode page 15 particularly suit able for spatially resolved studies The image plane of the sample is in coincidence with the entrance plane of the analyzer The user can define the acceptance area of the ana lyzer with the entrance slit As the trajectories of electrons emitted from the sample are influenced by electrical fields around the sample T1 has a fixed potential which is set to ground after switching on the power supply Due to lens aberrations rays entering the lens far away of the lens axis at larger angles could find a path to the analyzer en trance With an Iris aperture these bad rays can be eliminated Furthermore the Iris Aperture can be used to continuously adjust the angular acceptance of the analyzer For small spot a
71. ron Spectroscopy The spectrometer and the sample are connected to ensure that the Fermi energies are at the same reference level The binding energy of the electrons is given by E pn hv E hin W Pos 25 The energy E kin see figure 20 is measured by the spectrometer and after calibrating the work function of the spectrometer the binding energy of the sample relative to the Fermi level can be measured without knowing its work function because E iwf kin sample z E m Wf 26 spectr Typical values of the analyzer work function are between 4 eV and 5 eV The compensa tion is performed by addition through the software see SpecsLab software manual For fine adjustment use UPS mode measurement Please check the analyzer settings in 34 PHOIBOS S P E C e Work Function the SpecsLab2 program Adjust the desired voltage ranges separately select the voltage range in the analyzer settings before the measurement Please take note of section 7 4 Work Function Calibration with UPS on page 61 PHOIBOS 35 PHOIBOS SPECS Chapter Installation 4 1 Unpacking All analyzers and associated electronics are carefully packed before leaving the factory Carefully examine all packages for damage especially the shock and tilt sensors inside and outside the transport container If damage is suspected please contact SPECS imme diately for further instructions on what to do next The analyzer should remain in its protectiv
72. ry Value Be EIC 10R5a a 100R5a3 Value name ri 100 R5b CounteiChanneMask iC 100 Re ce Gi 100 RSINA N e da m C3 150R4 0000 00 7C mg 150R5 i 150R5GAS C 150 R5a i Cg 150R523 fy 150 R56 2 150 R5c MCD 8 ScanModes m C3 sco 1 Phoibos Hsa3500 RiceSpin E Hsa35004nalyzer_2 20 E C Hsa3500CedAnalyzer Cancel HG Poul00Detector_2 20 H E SpecsLab2 XMLSerializer sls My ComputeAHKEY_LOCAL_MACHINE SOFTWARE Specs H a3500Analyzer Phoibos H233500 150 R5c O 005b8d80 6000000 007c Figure 36 CounterChannelMask for MCD9 1 2 8 9 off 9 3 2 1 Mask example for MCD9 The reg CounterChannelMask entry for a MCD9 type PHOIBOS 150 R5c looks like Each bit represents one channel A 9 channel MCD for example has following mask 00000001 11111111 or as hexadecimal 01 FF Please note that the first bit from the left is channel number 1 and the last to the right is channel 9 or 5 respectively Therfore all channels means HKEY_LOCAL_MACHINE SOFTWARE Specs Hsa3500Analyzer Phoibos Hsa3500 150 R5c CounterChannelMask 01 ff To achieve that a 9 channel detector only use 5 channels you have to change to 00000000 01111100 or 00 7C The reg file for a MCD9 with channel 1 2 and 8 9 switched off looks like following HKEY_LOCAL_MACHINE SOFTWARE Specs Hsa3500Analyzer Phoibos Hsa3500 150 R5c CounterChannelMask z 00 7C 78 PHOIBOS SPECS un PHOIBOS 9 3 2 2 Mask example for MCD5 The reg Co
73. s check spectra without excitation source 2nd disconnect the preamplifier and measure again see Chapter 9 Table 11 High Background Signal possible cause perform check test or troubleshooting PHOIBOS SPECS PHOIBOS Possible Problems procedure no gt incorrect detector preamplifier threshold 2 section 9 1 1 and section 3 5 3 high noise of the primary source use a second excitation source electric interference monitor mains voltage check ground connec tions gt section 4 7 Table 12 Noisy Spectrum possible cause perform check test or troubleshooting procedure no gt malfunction of lenses Check tubus voltages section Check all ana lyzer HSA 3500 voltages on page The voltage can be measured either at the 12 pin feedthrough gt figure 33 on page 72 or at the rear of the HSA3500 Note table 2 on page 16 improper adjustment of the Slit Orbit mechanism check proper adjustment gt section 3 4 section 4 4 magnetic fields section 3 3 and section 4 4 Table 13 Incorrect area was analyzed in all lens modes 55 PHOIBOS SPECS Chapter Calibration Adjustment and calibration of the power supplies has been performed at the factory Normally no additional work is necessary after installation The procedures described in this chapter are only necessary for service and fine adjustment The ty
74. s algorithm is unequivocal because there is never more than one nominal energy between two measured energy positions Due to the interpolation routine there is no restriction on the energy step due to analyzer performance Power supply performance DAC steps etc limit the possible step widths and ranges The software validates the values to the nearest allowed values PHOIBOS S P E C S amp Single and Multichannel Detector SCD MCD PHOIBOS 3 5 3 Electron Multiplication A Channel Electron Multiplier channeltron or CEM is a high gain device for detecting energetic particles such as electrons and ions or radiation The CEM consists of a small curved glass tube The inside wall is coated with a high resistance material The resistive material becomes a continuous dynode when a potential is applied between the ends of the tube The impact of a charged particle results in secondary electrons that are released from the CEM wall These electrons are accelerated by VOS the high voltage connected to the CEM and release additional sec Lac ondary electrons by impact with the wall further along in the CEM This effect is repeated successively until finally an electron cloud is present at the exit of the CEM The average number of electrons leaving the CEM assembly per in cident particle is called the gain G For single particle detection the gain has to be selected high enough to use the CEM s in saturated operation i e
75. s of all particles independent of the kinetic energy are measured with the same resolution and the intensity decreases with the kinetic energy 1 I 12 E kin i i The two modes are generally possible for all kinds of measurements There are some applications where one of them is traditionally preferred The FRR mode is mostly used in AES ISS and is convenient for the measurement of a survey spectrum The FAT mode is mainly used in XPS and UPS when detailed information is needed and the resolution should not be dependent on the energy If Exin is kept constant and the same peak is measured with different pass energies it follows that I E 13 pass 3 3 Magnetic Shielding Because charged particles are influenced by stray magnetic fields including the earth s magnetic field it is essential to cancel these fields within the enclosed volume of the analyzer The analyzer the lens system and the detector are surrounded by one layer of 1 5 mm thick metal to screen the external magnetic fields down to an uncritical level The shielding factor for the analyzer region is about 35 For ultimate performance the analyzer and the lens system are constructed entirley from non magnetic materials in side the metal shielding see also section 4 4 Alignment on page 40 PHOIBOS PHOIBOS qm Figure 10 PHOIBOS u Metal Shielding 3 3 1 Magnetic Coupling for p Metal Chambers A proper shielding of the front of the lens and the
76. sary pulse height can be checked usually between 2 10mV see section 9 1 2 Amplifier Check on page 76 For the PHOIBOS analyzer an input of one electron to the CEM produces an output pulse that contains at least 107 electrons and lasts for approximately 10 nanoseconds 3 5 3 1 Extended CEM The standard detector systems of the PHOIBOS analyzer series are based on the exten ded range CEM This device is a specially formed and treated glass tube which has the effect of multiplying a single electron at the input to a pulse of around 10 electrons at the output Because of the low resistance about 50 MQ the extended range CEM s are suitable for extremely high count rates A voltage between 2 5 3 5 kV across the cone and the tail end initiates the electron multiplication Electron multiplication is produced by the emissive layer along the inner 29 CS PACS 30 surface of the channel The gain is governed by the detector voltage and the condition of the emissive layer The condition of this layer changes with usage and to compensate for a drop in emissive quality of the surface an increased detector voltage can be ap plied keeping the overall gain constant If the detector voltage has reached the limit of 3 5 kV the CEM is at the end of its life and needs replacing Lifetime of the Extended Dynamic Range CEM c x 9 o o o gt o 2 o 2 o a 250 5 1015 1000 2000 3000 4000 5000 6000 7000 Accumulated co
77. screws at the top plate and remove the plate PHOIBOS S PAC S Multiplier 4 x ceramic rods Disconnect the cables Note the orientation and alignment of the defective channeltrons Release the screws which are fixing the ceramic rods Release only one of the adjustment screws Do not change the other screws this fixes the position for the channeltrons with respect to the body when rebuilding the assembly figure 37 page 83 Pull back the ceramic rods until the replacement of the channeltron is possible figure 38 page 83 If the ceramic rod is stuck try to loosen the screws of each channeltron a bit Remove the channeltron Put the new channeltron in place and rebuild in reverse order Carefully fasten the connections with the screws Note A bad contact means noisy channeltron Check all channeltrons for proper mounting Check all electrical connections Figure 33 Schematics of the 12 pin Analyzer Feedthrough page 72 to remove the ceramic rods lose if necessary Figure 38 Pull back the Ceramic Rods Remove the Channeltron 10 2 2 3 Mounting the Detector Flange e Mount the detector flange in reverse order e Check that there is no short circuit for all the pins of the detector supply feed PHOIBOS through to each other and to ground 83 Spare Parts 84 SPECS Looking into the opened detector flange from the bottom side you can locate a alignment hole which corresponds to the part at t
78. sentially constant Eventually a point is reached where ion feedback becomes significant due to very high gain and the count rate increases rapidly This will significantly reduce the lifetime of the channeltron The Default Detector Voltage is normally given in the specification protocol of the ana lyzer and should be changed carefully A detector scan gives the actual status of the detector unit see Figure 15 Detector Sweep Count rate vs Voltage on page 29 Note 27 Spectrometer S P E C S R 28 Please choose a moderate end value of the detector voltage scan to prevent rapid aging of the detector The optimum operating point is about 50 100 V beyond the plateau of the curve fig ure 15 page 29 As the multiplier ages the knee moves to the right and the voltage must be increased In general CEM lifetime see figure 16 page 30 depends on the number of counted electrons thus it will vary as a function of specific application and environment but is typically on the order of about one year at 40 hours operation per week For multi channel detection systems each channel should be displayed The start value for the detector voltage for counting depends on total number of accumulated counts see section 3 5 3 1 Extended CEM on page 29 and the threshold level of the preamplifier The sensitivity of the preamplifier channels can be varied using a discrim inator threshold the value is factory preset recommended discriminator
79. si ene uto dia enidan Aei aara sia aeaee 47 52 Quick Start TERT PEE 47 53 Detailed ODSretibblusssss ecc nipeidbiidsaue cisadicas Erden ccds 48 5 3 1 Site S SUGMAG PS RI 48 5 3 2 Detector Operatlof 1 odiis aA EANA RARR 48 5 3 3 Functional TeSt cccccccccccseceeeeessseeeceeeeseeceeeeueeesseeeeeeeueeeeeeseeeeasseseeeeeees 49 53 3 1 XPS AES UPS Operation eessesesseeeeeeeeeee eene 49 5 3 3 2 ISS Operati My ect Ee EORR ae S RAINER codes AAA aaae 50 6 Troubleshooting 51 m SIMON CU ROO ET EENTT 51 6 2 Possible Problems eese easet eoo a n nbssas DEEP De cnn SEI TRUE 51 7 Calibration 57 7 1 Complete Calibration Procedure eesssseeeee 58 7 2 Recalibrate the DAC Precision eeeennn 59 4 3 MCD YAN NNI EER 60 7 4 Work Function Calibration with UPS eene 61 7 5 Work Function Calibration with XPS eee 62 7 6 Offset Calibration with UPS eesseeeeeenn n 62 7 7 _ Gain Calibration with XPS cocci coccacsceccacactacdesasanceeccntteandacs 64 8 Analyzer Checks 65 8 1 Independence of Peak Position with Pass Energy 65 8 2 Energy Scale Tests with XPS cccccccsssseeccesssseeeesssssnseeeeeeeeees 66 8 2 1 Check Kinetic Energy Scale erento recen eoi nnn nde 66 8 2 2 Check Peak Position eeeessseseeeeeeen nennen 66 8 3 Specification CHECK ccc
80. strip must be provided with a protecting device according to and meeting all safety regulations 3 A grounding bar copper brass with a minimum cross section of 6x6 mm has to be installed inside the cabinet The electronic unit has to be connected to this grounding bar 4 The grounding bar inside the cabinet has to be connected to the system e g to the analyzer housing by a ground cable of a minimum cross section of 10 mm The connections between analyzer control unit and computer are described in section 2 2 Electrical Connections on page 6 All connections described above have to be made before the initial operation of the system 4 8 SpecsLab Hardware and Software Installation Read the instructions e g section 2 2 Electrical Connections on page 6 and Spec sLab2 Chapter 1 Installation carefully before installing SpecsLab2 and evaluation pro gram You will find the manuals and other instructions in pdf format on the installation CD as well Please do not hesitate to contact SPECS for more detailed information supportGspecs de or phone 49 30 467 824 0 or 88 PHOIBOS S P E C S amp SpecsLab Hardware and Software Installation PHOIBOS 45 PHOIBOS SPECS Chapter 5 1 Unit Operation First Operation If the system is baked see section 4 6 Baking Out on page 43 the vacuum should be checked The base pressure should be lower than 10 mbar for more details please see section 5 3 3 Fun
81. tage transfer lens was designed to yield ultimate transmission and well defined optical properties It may be operated in several different modes for angular and spatially resolved studies to adapt the analyzer to different tasks All lens modes can be set electronically A lens system with the variable Slit Orbit mechanism is necessary to e image the sample plane on the HSA entrance plane e define the analyzed sample area and the accepted solid angle on a sample e accelerate decelerate the particles with the observed energy to the pass en ergy The standard working distance of 40 mm and the 44 conical shape of the front part of the lens provide optimum access to the sample for all kinds of excitation sources At the lens stage the particles emerging from the sample S are imaged onto the entrance slit S1 with the sample being in the focal plane of the lens system i e 40 mm in front of the first lens electrode T1 Inside the lens stage the particles pass through an intermedi ate image before they are focused onto the input slit S1 of the hemispherical capacitor figure 5 At S1 the particles have been retarded by the energy difference between the nominal particle kinetic energy Ec and the nominal pass energy Epass PHOIBOS PHOIBOS If S1 has the dimension D1 then by theory the imaged area of the sample has the dimension DS with DS D1 M 1 The magnification of the lens stage is selectable see table 2 on page 16 The magnific
82. tem CEMs and PCU 300 detection electronics From pulse height distribution measurements the findings are that the mean gain from the extended range CEMs is much less sensitive to increases in the true count rate This is the reason for the extended working range The detector voltage required to operate the extended range type CEMs is 300 V higher than that for the standard CEMs The high current AES survey spectrum shows the high count rate capability of the PHOIBOS detection system with the extended dynamic range CEMs 3 5 4 Conversion Energy The detection efficiency of a CEM with respect to a particle is defined as the probability of this particle or photon producing an output pulse The detection efficiency curves for electrons positive ions and UV light in figure 19 are based on published data and allow an approximate estimation of the efficiency in the given energy and wavelength range PHOIBOS PHOIBOS Single and Multichannel Detector SCD MCD es BS en eBncl im Ett o iE Lu Lm Detectie Detect sitiv ions Figure 19 Detection Efficiency for Electrons and lons The BIAS voltage produced in the HSA3500 determines the conversion energy E q U sas tE 23 conv pass of the charged particles impinging on the CEM The proper conversion voltage has two requirements which must be simultaneously fulfilled e the particles energy should be suitable for maximum yield of secondary electron e
83. threshold of the noisy channel to higher value up to 10 mV This will also shift the working point for the channeltron see The Working Point of the CEM s on page 27 If this does not help completely suppress the channel To continue to work with the analyzer up to the replace of the defective part without the signal from the noisy channels e Suppress a noisy channel section 9 3 1 e Switch off certain channels section 9 3 2 9 3 1 Suppress a Noisy Channel In some cases a channeltron becomes noisy dust contamination overheated etc To avoid disturbing the acquisition of the other channeltrons increase the threshold level for this channel Figure 26 Menu Analyzer Settings page 54 Note You have to se lect the desired channel first before changing the value to 120mV maximum for ex ample To reset all channels to the same value select all 9 3 2 Switch off Certain Channels To switch off certain channels it is necessary to modify the registry entry for the HSA3500Analyzer key For a 150R5c type of analyzer the entry CounterChannelMask is located at HKEY_LOCAL_MACHINE SOFTWARE Specs Hsa3500Analyzer Phoibos Hsa3500 150 R5c The necessary type is binary Create such a binary entry if it does not exist Figure 36 CounterChannelMask for MCD9 1 2 8 9 off page 78 Please also refer to the descrip tion about the registry entries in the SpecsLab2 manual The software masks not only the channels but the detec
84. tor shifts and channel gains too In the selection for the channels in the SpecsLab2 analyzer settings menu the con secutive numbering of the remaining channels start with 1 and end with the number of the available channels Note After any hardware change i e channel replacement or any registry change as above it is recommended to perform an MCD Calibration routine 77 Deflector Settings S PE C S g Registry Editor BEES Registy Edit View Help EH Specs Name Data S CCDDelector ab Defaut value not set 5 C3 CorbaServers aB DetectorVoltage 1800 C DeviceNetServer E EnableHiddenModes 0400000000 0 Gy Hsa8500Analyzer atf MaxCountFiate 0x005b8d20 6000000 Gl Phoibos Hsa3500 a 100R3 SPIN 100R4 100 R4MOD 10085 5C 100 R5a 100R5 amp 3 aS 100 R5b amp C3 100 R5c H 100 R5INA aS 150R4 180R5 a 150R5 GAS Hg 150 R5a a 150 R533 Cj 150 RSb o 150 R5c amp MDs E ScanModes B scp E C Phoibos Hsa3500 RiceSpin DWORD Value cGy Hsa350DAnalyzer 2 20 E Hsa3500CedAnalyzer m Peu300Detector_2 20 m SpecsLab2 m XMLSerializer zs Adds a new binary value p gl Registry Editor MEE Begisty Edt View Help B Specs a Name T Data CCDDetector ab Defaut value not set 56 CorbaServers E Detectoivotage mair E DeviceNetServer 3 EnableHiddenModes 0400000000 0 Gy HsadS DAnalyzer E Phoibos Hsa3500 EC 100 R3 SPIN aE 100R4 f 100 R4MOD m C3 100R5 Edit Bina
85. tron array array of 5 or 9 of single channel multipliers fused together in a precision matrix is a high gain device for detecting energetic particles such as electron and ions or radiation The channeltron consists of a small curved glass tube The inside wall is coated with a high resistance material The resistive material becomes a continuous dynode when a potential is applied between the ends of the tube It is fabricated from a lead doped glass Proper handling is required and the following precautions must be taken 10 2 1 1 Handling of the Multiplier e Shipping containers should be opened only under clean dust free conditions e No physical object should come in contact with the active area of the detector The channeltron should be handled by its solid borders using clean decreased tools fabricated from stainless steel teflon PTFE or other UHV compatible materials 81 Spare Parts 82 SPECS e The channeltrons should be protected from exposure to particle contamination Particles which become affixed to the plate can be removed by using a single hair brush and an ionized dry nitrogen gun 10 2 1 2 Operation of the Multiplier Microchannel plates and Channeltron detectors can be degraded by exposure to various types of hydrocarbon materials which raise the work function of the surface causing gain degradation Operation in a clean vacuum environment of 10 mbar or better is necessary in order to ensure the long life c
86. tting PHOIBOS SPECS PHOIBOS Offset Calibration with UPS Note the voltage range used while measuring For adjustment the desired range should be selected according to the used method i e 40V 400V 1500V or 3500V in the active method row of Analyzer settings see SpecsLab2 menu Analyzer Settings 1 Warm up the HSA3500 at least 10min Switch off and on again to reboot and force a startup calibration or manually perform the recalibration of the DACs section 7 2 on page 59 Set the voltage range for the UPS measurement mode in the Menu Analyzer Settings see Figure 26 to 40V Switch to the binding energy scale Measure the position of the fermi edge e g 0 2 to 0 2 eV binding energy and select Hel if He of course is used in the dummy source of the Menu Analyzer Settings Sources selected The tool Op eration Fermi Edge in the SpecsLab2 program as well as the cursor and differ ence cursor cross black red cross icon left right mouse button simplifies the procedure Note the comments given in section 7 4 Work Function Calibration with UPS on page 61 Use this 40V range result as the reference point for the other voltage ranges Select one of the other voltage ranges 400 1500 3500V in Menu Analyzer Set tings and perform a Fermi edge measurement like for the 40 V range Compare the result with the 40V range spectra Calculate the energy difference between expected and measured Fermi edge the us
87. ual difference is less than 0 2 eV more suggest a hardware error Set the offset for the selected voltage range use binding energy values to get the cor rect polarity for the offset Set the offset of the used energy module to the calculated value in the menu analyzer settings Measure again and repeat the procedure for each of the other desired voltage ranges Note the advice given in section 7 2 Recalibrate the DAC Precision on page 59 Yn np a SES Best Bi Sc T 8 ss 2 BRA i Oe Om xie JE PHOIROS 150MCD SHAD EF 5 334 me PAHM 01 1 9 56 eV hive pen ErewySko EreeyEnd bc E pam posa nE oc T 02 015 04 T T T T aos i 006 01 0 15 Ending Energy Ier NNNM Figure 30 Fermi Edge Operation 63 Calibration SPECS 64 For more detailed information please contact SPECS support 7 7 Gain Calibration with XPS See section 8 2 1 Check Kinetic Energy Scale on page 66 Run spectra for the gold and the copper peak use clean samples sputtered Measure the distance between the peak maxima of gold and copper If the value found differs strongly from 848 66 eV please inform SPECS You can correct the gain default value 1 by _ distance 27 gam 348 66 eV en Note the default voltage range you have used while measuring with the desired meth od see SpecsLab2 menu Analyzer Settings PHOIBOS PHOIBOS
88. um of silver enclosed with the Specification Report on the analyzer For example Excitation Mg Ka X ray power 300 W Slit entrance largest slit exit open Mode Medium Area Binding energy range 1000 0 eV Energy step 300 meV Dwell Time 100 ms Pass energy 13 eV A typical XPS overview spectrum taken with a PHOIBOS analyzer on silver is shown be low figure 31 67 Analyzer Checks S P e C S 68 PHOIBOS Hemispherical Energy Analyzer Friday December 21 2001 17 40 17 E i T 08 Kinetic Energy 10 eV J kom ponen ten phoibos 150 yrorknanuals Bilderixps ban Group Region Method Lens Slit Mode s 300W Overview 30 MA13 XPS MA 2 7x20 2 open FAT 1253 6 200 1267 4 Pei Figure 31 XPS on Silver Wide Scan PHOIBOS 150 MCD9 Parameters for the survey spectrum in figure 33 Lens mode Medium Area Slit entrance largest slit exit open Sample current 160 nA at 300W Mg Ka 8 3 2 Intensity and Resolution Use the same settings as in the Ag spectra enclosed with the Specification Report on the analyzer For example Excitation Mg Ka X ray power 300W Slit entrance largest slit exit open Mode Medium Area Bin energy range 378 364 eV Dwell Time 100 msec No of scans 1 Step width 25 30 meV Pass energy 8 9 eV A well resolved Ag 3d doublet is shown in figure 32 This spectrum is typical
89. unterChannelMask entry for a MCD5 type PHOIBOS 100 MCD R5c looks like A 5 channel MCD has following mask 00000000 00011111 or as hexadecimal 00 1F Please note that the first 1 from the left is channel number 1 and the last digit on the right side is channel 5 respectively Therfore all channel means HKEY_LOCAL_MACHINE SOFTWARE Specs Hsa3500Analyzer Phoibos Hsa3500 100 R5c CounterChannelMask z 01 1F To achieve that a 5 channel detector only use channels 1 2 and 4 you have to change to 0000000 00011010 or 01 10 i e HKEY_LOCAL_MACHINE SOFTWARE Specs Hsa3500Analyzer Phoibos Hsa3500 100 R5c CounterChannelMask z 01 10 79 PHOIBOS SPECS Chapter 1 0 Spare Parts 10 1 Cu Gasket All CF gaskets are custom made by SPECS In case you need a replacement please con tact SPECS because it depends on the release of the analyzer The serial number of the analyzer is marked on the lens flange 10 2 Multiplier 1 SCD Single Channel Electron Multiplier replacement for PHOIBOS analyzer 2 MCD CEM Array replacement 5 channels MCD for PHOIBOS analyzer 9 channels MCD for PHOIBOS analyzer Please indicate the serial number of your analyzer flange at the lens housing e g 33 04 in the replacement order The order of a single channeltrons a set of channel trons or a complete replacement of the detector flange including channeltrons is pos sible 10 2 1 Channeltron Handling and Storage A channeltron or a channel
90. unts Gcounts Figure 16 Lifetime of the Extended Dynamic Range CEM e While a CEM is not counting residual gases in the system are adsorbed onto the channel walls which are kept clean by electron bombardment during opera tion e When initially running a new CEM it needs approximately 20 x 10 counts for conditioning Once properly conditioned or burned in the surface on the semiconducting glass channel is quite stable e The test results suggested that accumulations to 5 x 10 counts and higher can be expected without serious degradation e The extended range CEM s are suitable for extremely high count rates without serious degradation 3 5 3 2 Linearity of the CEM s Inadequate design may cause electron analyzers to show non linear behavior For an ideal counter with a non extended dead time t the measured count rate N and the true count rate N are given by N NI A N 1 20 With the PHOIBOS SCD analyzer the count rate as a function of the Auger electron beam current has been measured using both the standard and extended dynamic range CEMs For a non extended dead time counter the ratio N 1 N 2 of two spectra N 1 and N 2 measured at two different beam currents A x and I the spectral ratio is given by PHOIBOS S P E C S Single and Multichannel Detector SCD MCD N N A 1 A XtXN 21 Therefore from a spectral ratio plot the dead time can be determined The detection efficiency N 1 N1 can now
91. unts not cps Noise 3x c 3x signal counts 28 Normally the discriminator threshold does not have to be changed If necessary the threshold can be adjusted in the menu Analyzer Settings Increasing the threshold level causes a shift of the detector starting point and plateau towards higher voltages but helps to suppress possible channeltron differences noise etc Usual threshold val ues are in the range between 2 and 10mV 75 Deflector Settings S PE C S R 76 9 1 2 Amplifier Check 2 Run spectra Measure 3 Use a wire and touch with finger Io see counts a a Danger Disconnect HV cables en fe S 12 Chanel HV SPEC gl la CAN connection shows green LED Figure 35 PCU Amplifier Test Caution Set the detector voltage to zero and disconnect both HV cables CHANNEL HV and CHANNEL BASE Mind the safety information given at the beginning of this manual Disconnect the detector box preamplifier is inside from the detector flange Run a spectrum Touching each pin of the preamplifier connector with a piece of wire results in a signal A signal must be observed for each channel If no signal is observed for some channels these channels of the MCD preamplifier are not ok If no signal is ob served for all channels or a constant signal is observed check the preamplifier power green LED Note If the maximum count rate is achieved the measurement will stop To avoid
92. uter Jost Plate Tubus 4 7 not connected Tubus 8 Tubus 9 Tubus 10 Ground Plate PIN 10 Inner Hemisphere PIN 11 Outer Hemisphere PIN 12 Coil Analyzer connector Figure 33 Schematics of the 12 pin Analyzer Feedthrough 72 PHOIBOS PIN 1 PIN 2 PIN 3 PIN 4 PIN 5 PIN 6 PIN 7 PIN 8 PIN 9 PIN 10 PIN 12 Channel Base Cathode Signal Channel1 Signal Channel 2 Signal Channel 3 Signal Channel 4 Signal Channel 5 Signal Channel 6 Signal Channel 7 Signal Channel 8 Signal Channel 9 Channel HV Anode Figure 34 Schematics of the 12 pin Detector Feedthrough 8 5 Check all analyzer voltages This section has been moved to the HSA3500 Manual PHOIBOS Connection Check of the Analyzer Electrodes 73 PHOIBOS SPECS Chapter Deflector Settings 9 1 Preamplifier 9 1 1 Discriminator Check the discriminator threshold using the noise of the signal within one spectrum The square root of the signal counts not counts second should be equal to the RMS root mean square of the noise at this energy i e the value mean signal 3 x RMS should include nearly all data points The noise value without excitation source should be only few counts per second and channel Threshold Value Use the fixed mode of the acquisition software see SpecsLab2 manual to estimate the noise at constant kinetic energy for the acquired signal and compare with the square root of the signal co
93. whether on Ag sample photo current 20 2 0 3 nA W sample is dirty sputter until C and O peak in the spectrum disappears sample too rough remove roughness incorrect analyzer sample distance adjust distance to 40 mm lens system and HSA out of focus check lens and HSA electrodes gt section 8 4 and voltages section CEM yield to low measure detector supply voltages section conversion voltage too low check conversion voltage section 3 5 4 MCD preamplifier setting changed check preamp settings section 3 5 3 some channels of the preamplifier unit defective check operation of the preamplifier by use of a separated channel mode of the software or 2 section 9 1 2 magnetic fields Check whether the amount of the deviation depends on the energy of the measured elec trons and on the pass energy better by UPS Check the influence of an external permanent magnet near the vacuum chamber physically incorrect adjustments like gridsdamaged lenses misaligned Open analyzer system and check Do this only if all other kinds of faults can be excluded PHOIBOS SPECS PHOIBOS spheres shifted MCD shifted Possible Problems improper adjustment of Slit Orbit mechanism check proper adjustment section 3 4 Table 6 Low Intensity possible cause perform check or troubleshooting procedure no gt test chemical peak broadening
94. ws the standard lens modes of operations Additional acceleration modes for low kinetic energy applications are also available HighMagnification2 and SmallArea2 tion Spatially resolved Entrance slit size divided With Iris aperture continuously Small area XPS UPS by M independent of adjustable from maximum to standard ARXPS analyzer settings 1 and ARUPS Slit sizes 7x20 3x20 1x20 0 5x20 0 2x20 27 3 and 1 mm High Magnification Magnification M 10 Up to x9 Medium Magnification Magnification M 2 5 Up to x6 Low Magnification Magnification M 2 Up to 3 Transmission optimized Optimized for different Large Area XPS spot sizes of the source Monochromated Typical spot size XPS Large Area Medium Area Small Area Angular resolved High Angular Dispersion Medium Angular Dispersion 5mm Up to x5 2mm Up to 7 0 1mm Upto um Slightly decreasing with Entrance slit size divided byD increasing retarding ratio and independent of slit sizes tings Slit sizes 7x20 3x20 1x20 0 5x20 0 2x20 7 3 and 1mm independent of analyzer set D 3 2 mm x3 acceptance D 2 2 mm x4 acceptance AES ISS and syn chrotron studies Low kinetixc energy applications ARXPS ARUPS with a 2D detection system Angular Mapping Low Angular Dispersion Wide Angle Mode D 1 2 mm x7 acceptance D 2 0 5 mm x13 acceptance Table 2 Overview of the Lens Modes For small spot an

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