"user manual"
Contents
1. uerennsnnne 37 7 1 3 1 Check the cable contacts nee eee annees 38 7 1 4 Check HSA voltages entere t tea p deve 38 7 1 5 Preamplifier Check 4 oer ete e EEE EEEE 39 7 1 5 1 DiSCHimniN ator o rier rere RAE ERE PR RARE re Tee rA PEE Sek nie 39 7 1 5 2 Amplifier Check oe eerie eH 39 7 2 Detector setings proa yit EISE re eR 40 PHOIBOS 7 2 1 Preamplifier 2 2 nane nete anra ettet 40 7 2 2 Detector Voltage eire E ER m eerte tete 40 7 3 WORK FUNCTION ieii 1 0 nter E or rto isses 40 8 Spare Parts 41 8 1 Cu G sket nire eR ce a tt 41 8 2 Multiplier stain oen tr EE ER E e ee 41 8 2 1 SCD multiplier replacement sesenta 41 8 2 2 MCD CEM Array replacement uunseesesseeseensersnensnesnennnesnnnnnenennnennnnnn 41 8 2 3 Channeltron Handling Storage and Operation sss 41 8 2 4 Handling eoe el ehe 41 8 2 4 1 Storage Multiplier ope UR en Mie Ond UU 42 8 2 5 Change Mult plietr 5 entente prie 42 8 2 5 1 Removing the detector flange esee 42 8 2 5 2 Changing the channeltrons eese 42 8 2 5 3 Mounting the detector flange esee 42 9 Appendix 45 9 1 Unpacking onusta he Recargar 45 9 2 Vacuum Installation eese eene nennen nnne 45 PHOIBOS I PHOIBOS Chapter Introduction The SPECS PHOIBOS hemispherical electrostatic energy analyzer allows recording of energy2. 8 PHOIBOS Basic Spectrometer Description Viewport for Alignment DN500CF Variable Slit Drive Electrical Feedthrough Figure 6 Analyzer vacuum housing PHOIBOS 150 PHOIBOS 9 Description hemispherical capacitor with radii T10 multichannel 2202 detector T9 assembly lens ra system T7 T6 E T5 E T4 T3 E e T2 Q e EN Y ZT y lt Sample Figure 7 T1 to T10 S1 S2 IH OH I C1 to C9 Main components of the spectrometer electrodes of the lens stage hemispherical capacitor entrance slit hemispherical capacitor exit plane inner hemisphere outer hemisphere nominal capacitor radius 150 mm discrete collection single multichannel detector 1 5 or 9 channels multichannel assembly MCD 10 PHOIBOS Basic Spectrometer Description Uo Figure 8 Collector Anode 100V U Anode Cathode Analyzer Voltage Principle Uo main retardation voltage numerically equal to kinetic energy of the detected particles U slit potential gt numerically equal to pass energy U Anode anode potential Ur main transmission voltage d detector voltage Uconv conversion voltage T1 T10 lens potentials IH OH inner outer hemisphere 2 3 1 The Lens System A lens system with the variable Slit Orbit mechanism is necessary to e image t
3. Parameter for the survey spectrum in figure 11 Lens mode Large Slit 6 x 20 mm Sample current 128 nA Detector voltage 2400 V Conversion voltage 128 V 28 PHOIBOS Typical Spectra Ag 3d peak 3007 Mg Kalpha 250 kCps a um Intensity t ea 50 SPECS Customer Service Sage 150 stefan phoibor rilwer jd ex Height 21308 T T T T T T T T T T 858 870 B72 874 876 aa 850 802 884 886 Kinetic Energy eV Mg Method Lens Start End Step scans Dwell Pass Date Time Tag ae xes m ser 02 s887 01 0 050 S 0 10 11 2Z apr 1999 18 00 00 SPECS Zr apr 2333 Ir sm aa Figure 12 XPS on silver Ag 3d PHOIBOS 150 SCD Parameter for the Ag 3d spectrum in figure 12 Lens mode Medium Slit 6x 20 mm Sample current 140 nA Detector voltage 2400 V Conversion voltage 128 V PHOIBOS 29 Analyzer Test 30 PHOIBOS Chapter Troubleshooting Procedure In the following a list of possible problems or anomalies and hints for their removal is given It is assumed that the system was calibrated properly and was working according to the specification before one of the following problems occurred 6 1 Possible Problems The following problems may occur during operation of the analyzer system no spectrum low intensity low resolution peaks shifted intensity fluctuations high background signal noisy spectrum wrong analyzed area Slit Orbit pro
4. Perform a crosstalk test with all lens tubes section 7 1 3 1 maltunction of the energy sweep check the energy sweep generator section 7 1 1 1 section 7 1 Table 11 High Background Signal possible cause perform check test or troubleshooting procedure no gt eld emission at the exit slit o the HSA AE const rises with small Epass Values and increases in AE E const mode Remove wire edge from the mesh at the exit slit of the CEM E const mode and background to signal ratio decreases with increasing of the pass energy alse detector preamplifier threshold gt section 2 3 5 Table 12 Noisy Spectrum Possible Cause perform check test or troubleshooting procedure no gt alse detector preamplifier threshold section 2 3 5 1gh noise of the primary source on silver sample by different Epass measure signal at the Ag 3ds peak 368 eV bin energy and noise at the 353 eV bin energy gt signal to noise ratio is independent of E electric interference monitor mains voltage check ground connec tions gt section 3 3 Table 13 Wrong analyzed area in Small Medium Large mode possible cause perform check test or troubleshooting procedure no gt malfunction of lenses sured either at the 12 pin feedthrough figure 3 on page 6 1mproper adjustment of the check proper adjustment section 4 1 Slit Orbit mechanism 34 PHOIBOS Chapter Power Supply Check and Settings En nene
5. Sl S2 6 x 20 mm 6 x 20 mm diam 6 mm 6 x 20 mm 4x 15mm 4x15 mm diam 4 mm 4x 15mm diam 1 mm 1x3mm PHOIBOS 15 Description For a given energy resolution and a given tolerated analysis space area and acceptance angle the largest possible slit area should be selected This enabled the highest possible count rate for this parameters and therefore either a short measurement time or a good signal to noise ration in a given time The slits are arranged in a row on two slit planes which located in the entrance and exit planes of the hemispheres When the external rotary dial is turned the slit plates move together across the entrance and exit planes of the hemispheres The possible range is fixed by mechanically stops Although the entrance and exit slits are usually identical the above combination and other combinations may be specified within a pair The resolution is determined by the mean slit width 2 3 5 Single Channel Detector SCD Multichannel Detector MCD The detector consists of the following parts arrangement of Channel Electron Multipliers CEM 1 for SCD 5 or 9 for MCD consisting of discrete collectors specially screened against external HF signals for maximum noise rejection e multi pin ceramic high voltage vacuum feedthrough specially designed for low cross talk e SCD MCD preamplifier e high voltage divider for generating the voltages for the assembly 2 3 5 1 Principles Detection
6. by sweeping the spectrum once over the detector area 5 or 9 parallel spectra are recorded simultaneously As the kinetic energy E of the particles arriving at collector C is known from equation equation 14 the particle number from each channel belonging to the same kinetic energy can simply be added up resulting in a total particle number for each kinetic energy 2 3 5 2 Coherence E ass and Step pass From the analyzer energy dispersion equation the energy difference AE between neighboring channels at the distance AR one from another is AR AE D 7 E ass EQ x or E e AE EQ 17 pass AR k Q where D is the analyzer dispersion Especially in the CRR mode where the pass energy changes throughout the spectrum and so does the energy difference between neighboring channels a calculation of the detected energy of the particle is necessary Therefore a software routine calculates the particle number N in channel C at the nominal kinetic energy by interpolation between the actually measured numbers in channel C at the measuring energies nearest below and nearest above the nominal energy This 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 the analyzer performance Power supply performance DAC steps etc limit the possible step widths and range borders Therefore the
7. Due to the spherical symmetry of the HSA a one to one image of the circularly shaped entrance slit with curvature radius R exists in the exit plane for monochromatic electrons with a nominal pass energy Epass 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 Ro E UN E asi D nc EQ 14 Ro E Ro 7 where D is the HSA dispersion The theoretical value for D is D 2 R EQ 15 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 collectors with 5 or 9 exit slits on concentric circles in the exit plane The radial distance between neighboring exit slits AR is selected to meet the requirement of a constant kinetic energy difference between neighboring channels AE The number of particles N arriving at each collector C is counted separately and these numbers are stored and preprocessed in the data acquisition unit 16 PHOIBOS Basic Spectrometer Description By sweeping the spectrometer voltage Ug the spectrometer is moved across each collector channel step by step and in this way each collector records a complete spectrum with a fixed energy offset between neighboring channels Thus in principle
8. Kinetic Energy Check 7 1 1 1 Sweep generator The sweep generator is usually realized as a DAC board in the HSA 3000 There is normally no adjustment of the DAC necessary For more detailed information please contact SPECS To check the DAC please check the spectrometer voltage Uy refer to section 7 1 1 2 7 1 1 2 Check the spectrometer voltage Up For this check a digital voltmeter with a HV probe should be used Mind the safety hints given on page 2 Set kinetic energy to 0 eV note WF and start measurement in fixed mode with start energy 0 Connect a digital voltmeter with HV probe to the connector of the pin marked KINETIC ENERGY at the rear panel of the HSA 3000 power supply see Connection scheme of the PHOIBOS SCD components on page 4 Run a spectrum from 0 to 200 eV and observe the variation of the spectrometer voltage Ug If Up varies within the chosen energy range the spectrometer voltage generation is o k 7 1 1 3 Zero Check Set the work function in the software to zero Set the kinetic energy of 0 000 eV Set the multiplier voltage to 0 V Measure with the digital voltmeter 5 1 2 digit type Egin Check the output voltage of the HSA 3000 7 1 2 Check the voltage range of the HSA 3000 7 1 2 1 HSA 3000 range 3 kV Preparation 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 namely the A
9. L E Lens System 11 B Electrical Connections 3 Low Energy Resolution 32 Low Intensity 32 Baking Out 22 Basic Spectrometer Descrip F tion 7 M First Operation 23 MCD 16 C Multichannel Detector 16 Change Multiplier 42 H E oo S 2 Hemispherical Analyzer 12 N Co u tep High Background 34 Connection scheme of the housing 8 9 No Spectrum 31 PHOIBOS en f gt HSA 12 Noisy Spectrum 34 Connection scheme of the HSA 3000 Voltage Ranges 15 PHOIBOS SCD 4 Conversion Voltage 19 PHOIBOS a P Peaks Shifted Power Supply Calibrations S Safety Hints sampling areas SCD Slit Orbit Mechanism Spare Parts Specification Check Storage Multiplier System Description T Troubleshooting U Unpacking V Vacuum Installation W Work Function Wrong analyzed area X 33 XPS on silver 35 12 16 15 41 26 42 3l 21 21 20 34 28 PHOIBOS
10. at first operation after bakeout so care should be taken to use the detector not at full multiplier voltage and not at full intensity within the first operating hours after bakeout Recommended is a wait for complete cool down of the detector assembly of approximately 1 day We recommend a increasing of the detector voltage over a period of 1 5 hours for the first time and over a period of 10 min for the next times after bake out Use the SpecsLab mode Detector Sweep and set start end step and dwelltime parameter for this procedure Check with Validate the run time for this special measurement 22 PHOIBOS Chapter System Operation 4 1 First Operation If the system is baked see Baking Out on page 22 the vacuum should be controlled The base pressure should be lower than 1077 mbar see Functional Test on page 24 Check the electrical connections see Electrical Units Installation on page 21 4 1 1 Calibration of the Slit Orbit Mechanism There are different settings available with the PHOIBOS Slit Orbit mechanism see Slit Pairs on page 15 The counter clockwise turn will set to larger slits concerning the possible slit pairs for this analyzer The optimum setting is reached when entrance slits are aligned along the lens axis i e the particle number passing through the lens stages and impinging on the hemispherical capacitor entrance slit S1 is maximum This is also right the position
11. ee He ERE ERE te ieiti espe talo 22 3 5 Baking O t scant iue ee et Res PER He 22 PHOIBOS l System Operation 23 4 1 First Operation i sunm ete eee 23 4 1 1 Calibration of the Slit Orbit Mechanism eere 23 4 1 2 Detector Operation e ere e peret p peer pee 23 4 1 3 Functional Test rt REEL EE EIER ARE EE AS 24 4 2 Quick Operation nonien tie 24 Analyzer Test 25 5 1 Independence of peak position with pass energy eese 25 5 2 Kinetic energy scale test si sci nies aan 26 5 2 1 Preparation nietos ute ente ent reti ue e ect 26 2 252 Check Peak Position sisi cie cert re hn ere etre 26 5 3 Specification Check iecit lie e E pter eer etos 26 5 3 1 Survey Spectrum of Silver uenseescessessenssenseensnnsnennensnennonsnennnnnnennennenn 26 5 3 2 Intensity and Resolution cece ese ceseeseceecesecesceseeseeeseeeeeeseeeaeeneeeaeeaee 27 5 4 Typical Spectra Je ea ARE 28 5 4 1 XPS Em 28 Troubleshooting Procedure 31 6 1 Possible Problems 2 00 2 a ma anne 31 Power Supply Check and Settings 35 7 1 Control Unit Clieck rrt rtt ttr tereti nh 7 1 1 Kinetic Energy Check 88881 seen 7 1 1 1 SWEEP generator 1 e terere ee eee oo iet Pre od den ses sess 7 1 1 2 Check the spectrometer voltage Up 7 1 1 3 Zero Check ettet eres 7 1 2 Check the voltage range of the HSA 3000 7 1 2 1 HSA 3000 range kV u er ana ae 7 1 3 Connection Check for the HSA Electrodes
12. fully remote controlled The electrical connection diagram is given in figure 1 2 2 Electrical Connections All devices must be switched off before connecting or removing cables PHOIBOS Description filter unit 20M z 3 Z E z SSI 10 s SHSSIHASPIT ES E 2 Figure 1 Connection scheme of the PHOIBOS SCD components 4 PHOIBOS Electrical Connections 3199 87 Su u3ldlidAv3sd VSH NIAH D 2j AHS M31Nn02 100 AHP 1331300 Sd 3190 87 Su UalsMdNV3ud VSH NIAH D U3LNNOI NO AHo 1231300 td 3199 587 Su 3l dA 38d VSH NIAH D M31Nn02 10 AHD 1231300 4 3199 87 Su ualdlidWv3sd VSH NI AH p dua nno 100 AHP 133130 E 3199 S87 Su L Wild dWvaud VSH NAD IN dii31Nn02 100 AH 1931304 3195 ZEZSY E UWT LL L D NOYLTENNYHI zersa A SAO N m ILINW 331Nn02 JINIS YILNNOI tmi ADU3N3 2IL3NDI C y No Connection scheme of the PHOIBOS MCD components PHOIBOS Figure 2 Description The connection to the analyzer and the detector are supplied by 2 multi pin vacuum feedthroughs which are designed for high voltages up to 5 kV 1 A 12 pin feedthrough on a flange DN38CF mounted to the lens housing F3 from figure 6 for all voltages of lens electrodes and capacitor electrodes which is schematically shown in figure 3 view from atmospheric side PIN 1 Tubus 1 PIN 2 Tubus 2 PIN 3 Tubus 3 PIN 4 Tubus 44 5 PIN
13. spectra for negative particles electrons and positive particles ions in the kinetic energy range from 0 eV to 3 0 keV The PHOIBOS series of hemispherical analyzers is a range of hemispherical deflectors available in two sizes 100mm and 150 mm mean radii and an input lens designed to accommodate a wide range of applications The analyzer is equipped standard with a single and optional with a multichannel detector with 5 PHOIBOS100 and 9 PHOIBOS150 discrete channels The pulse counting electronics consisting of preamplifier pulse forming unit and 24 bit counter is supplied together with the analyzer control unit All units provide the detection of electron energies between 0 3000 eV with minimum step witdhs of 13 meV The unit can be upgraded by an additional voltage modules Hi RES module 0 300 eV with minimum step witdhs of 1 3 meV Super Hi Res module 0 300 eV max range 50 eV with step witdhs 0 2meV Beside the multichannel detection a variable magnification lens are available as option Due to the new SPECS Slit Orbit mechanism and a Multi Mode Lens the analyzer sampling area and lens acceptance angle area are selectable Thus the analyzer allowing confined area measurements down to 100 200 um area diameter as well as large area investigations accociated with different lens acceptance angles All units are completely controled by SPECS software Features and operation of the software will be described in a separate manua
14. work function because Ein Wf sample E kint Wf spectr EQ 20 20 PHOIBOS Chapter Installation 3 1 Unpacking Please see Appendix on page 45 3 2 Vacuum Installation Please see Appendix on page 45 3 3 Electrical 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 1 Mind the following 1 Connect all units to the same multiple socket 2 The outlet strip must be provided with a protecting line according to the regulations 3 A grounding bar copper brass with a minimum cross section of 6 6 mm has to be installed inside the cabinet The electronic unit except for MCD preamplifier have to be connected to this grounding bar by means of flat braided grounding ribbon which is connected to the back panels of the electronic unit 4 The grounding bar has to be connected to the screw at the analyzer plug of the spectrometer by means of a flat minimum width 10 mm braided grounding ribbon or a cable black isolation of minimum cross section of 10 mm The connections between analyzer control unit and computer are described in Electrical Connections on page 3 These connections have to be made before the first operation of the system PHOIBOS 21 Installation 3 4 Preliminary In case of XPS the analyzer and X ray source should be instal
15. 5 Tubus 6 PIN 6 Tubus 7 PIN 7 Tubus 8 PIN 8 Tubus 9 PIN 9 Tubus 10 PIN 10 Inner Hemisphere PIN 11 Outer Hemisphere Figure 3 Schematics of the 12 pin HSA feedthrough 2 The detector feedthrough and its pin assignments are shown in figure 4 Mounted on flange F5 from figure 6 DN 38CF seen from the atmosphere side PIN A Anode PIN T Tube Cathode PIN Fi Collector F1 Figure 4 Detector schematic connection setup and feedthrough pin booking view from atmospheric side 6 PHOIBOS Basic Spectrometer Description 2 3 Basic Spectrometer Description The PHOIBOS spectrometer consists of a vacuum housing and four major internal components which are shown in figure 6 and in figure 7 All the parts must be exist within Ultra High Vacuum environment as particles emitted from the sample surface could collide with the gas particles and so be lost from the study The internal components are input lens system for receiving charged particles e 180 hemispherical analyzer HSA with 100 150 mm nominal radius for performing spectroscopic energy measurements detector assembly for single particle detection e Slit Orbit mechanism with external rotary feedtrough The source of primary radiation 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 hemispherical analyzer they first pass through an electron lens system an
16. EM The electron cloud emitted out is finally post accelerated onto the collector electrode 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 component for the PHOIBOS analyzers The CEMs are all parallel mounted as a unit on a feedtrough flange The particles passing the exit aperture are post accelerated to an appropriate kinetic energy onto the CEM The operating point for channel electron multiplier CEM in the pulse counting mode is usually determined by the point at wich a plateau is reached in the count rate vs voltage characteristic The plateau occurs when all the signal is being collected at the input of the CEM Additional increases in voltage raise the gain but the count rate remains essentially constant Eventually a point is reached where ion feedback becomes significant due to the very high gain and the count rate increase rapidly This is an undesirable condition since the extra counts are produced within the CEM itself and are not the result of an input The optimum operating point is about 50 100 V beyond the knee of the curve As the multiplier ages the knee moves to the right and the voltage must be increased In general CEM lifetime will vary as a function of specific application and environment but is typically on the order of abo
17. I AE As AE QUA T o m EQ 9 kin kin where Q and Ag are the values of the acceptances for the HSA They are analyzer constants The equation results from Liouville s theorem The analyzer can be operated in two different modes a Constant Retardation Ratio CRR the retardation ratio B is defined as Erin EO 10 Tc EQ 10 pass B In this mode all particles are decelerated with this same fixed factor Therefore the pass energy is proportional to the kinetic energy The intensity is increasing with the kinetic energy IE EQ 11 while the energy resolution is decreasing b Constant Analyzer Energy CAE Epass and AE in according to equation 5 are adjustable constants The signals of all particles independent of the kinetic energy are measured with the same resolution The intensity is decreasing with the kinetic energy I L EQ 12 Ekin 1 For more informations 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 14 PHOIBOS Basic Spectrometer Description The two modes are both generally possible for all kinds of measurements There are some applications where one of them is traditionally preferred The CRR mode is mostly used in AES ISS and is convenient for the measurement of a survey spectrum The CAE
18. MCD preamplifier are o k If no signal or a constant signal is observed the cable connections between the preamplifier and the HSA 3000 and the preamplifier power must be tested 7 2 Detector settings 7 2 1 Preamplifier See section 7 1 5 Preamplifier Check on page 39 7 2 2 Detector Voltage Because of considerable gain spread of different multipliers the voltage needed for the signal and FWHM specification for the MCP installed may differ from the nominal value of 1700 V Pay attention to the detector voltage value in the Specification Report with the analyzer Basically a working detector voltage is the detector voltage at which FWHM of the Ag 3d5 gt peak is 0 90 eV see section 5 3 2 with sample and X ray source positions optimized 7 3 WORK FUNCTION Typical values of the analyzer work function are between 4 eV and 5 eV The compensation is performed by addition through the software see software manual 40 PHOIBOS Chapter Spare Parts 8 1 Cu Gasket Cu Gasket DN 350 CF 8 2 Multiplier 8 2 1 SCD multiplier replacement Single Channel Electron Multiplier for PHOIBOS analyzer 8 2 2 MCD CEM Array replacement SPECS order 79150134 5 channels MCD for PHOIBOS analyzer SPECS order 79150062 9 channels MCD for PHOIBOS analyzer 8 2 3 Channeltron Handling Storage and Operation A channeltron or a channeltron array array of 5 or 9 of single channel multipliers fused together in a precisio
19. Mg Ka X ray power 300W Slit 6x 20mm Binding energy range 1000 0 eV Energy step 300 meV Step time 100 ms Pass energy 20 eV a typical XPS overview spectrum taken with an PHOIBOS on silver is shown in figure 11 5 3 2 Intensity and Resolution Make the same adjustment as in the Ag 3d doublet spectrum enclosed with the Specification Report on the analyzer For example Excitation Mg ka X ray power 300 W Slit 6x 20mm Bin energy range 378 364 eV Step time 100 msec No of scans 10 Step width 25 30 meV Pass energy 6 0 eV the well resolved Ag 3d doublet is shown in figure 12 This spectrum is typical for an PHOIBOS The signal net intensity i e peak count above background of the Ag 3ds peak is about 200 kcps The background in this case is defined as a straight line between the two neighbor valleys on both sides of the peak The FWHM of the Ag 3ds peak is calculated by measuring the peak width at the half height between the peak maximum and the background Note Because of considerable gain spread of different CEM s the voltage needed for the signal and FWHM specification for the detector unit installed may differ from the nominal value of 2400 V see section 7 2 Pay attention to the detector voltage value in the Specification Report on the analyzer With sample and X ray source positions optimized the detector voltage at which FWHM of the Ag 3d5 2 peak is 0 90 eV is the working detector voltage If measured spec
20. SPECS Surface Analysis and Computer Technology PHOIBOS Hemispherical Energy Analyzer User Manual PHOIBOS 150 PHOIBOS 100 1 2 All rights reserved No part of this manual may be reproduced without the prior permission of SPECS GmbH User Manual for the energy analyzer PHOIBOS 150 and for the energy analyzer PHOIBOS 100 as well Version 1 2 of the 25 5 99 SPECS order number for this manual 78 000 101 PHOIBOS Chapter Table of Contents 1 Introduction 1 2 Description 3 2 1 System Descriptions iani deed te etd e aan 3 2 2 Electrical Connections iniu paene 3 2 3 Basic Spectrometer Description uu suessessnesnnessnnnnennennnesnnennnennennnn ern 7 2 3 1 The Lens System oett etre e pii eei tede etos 11 2 3 2 Hemispherical Analyzer HSA sese 12 2 3 3 HSA 3000 Voltage Ranges eee enne 15 2 3 4 Slit Orbit Mechanism eese nin a enne nennen enne ner ens 15 2 3 5 Single Channel Detector SCD Multichannel Detector MCD 16 2 3 5 1 Principles D tection rarnana en e A ae 2 3 5 2 Coherence Epass and Step 2333 Electron Multiplication eee 2 3 5 4 Conversion Voltage eto oe Redeem 2 4 Work Function runs 20 3 Installation 21 3 1 Unpacking o bite ted et pis 21 3 2 Vacuum Installation sin a E enne enne enne enne nnns 21 3 3 Electrical Units Installation o neinean ian aE ARTA OAAR 21 3 4 Preliminary 5 inier Heo t
21. and calibration of power supplies have been performed at the actory To proof the analyzer test that the peak position independent of pass energy kinetic energy scale and check the analyzer specification see section 5 Attention Before taking off any power supply cover and changing the trimmers set please consult SPECS Taking off the cover without a SPECS written consent will void the SPECS warranty Mind the safety hints given on page 2 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 control voltage from the sweep generator usually a DAC is missing The following checks should be made 1 Check the cable connections figure 1 figure 3 and figure 4 between counter and preamplifier as well as the connection between HSA 3000 and HSA and the PC and the HSA 3000 2 Control Unit Check see 7 1 3 Preamplifier Check see 7 1 5 4 Detector settings on page 40 7 1 Control Unit Check In this section a connection check for the contacts of the electrodes is made and the spectrometer voltage Uy is verified For this check a digital voltmeter with a HV probe and capacity measurement ability must be used The PHOIBOS 35 Power Supply Check and Settings voltages will drop slightly due to the loading by the voltmeter and HV probe resistance For these tests this is not important 7 1 1
22. blems The each statement following gt indicates a separate troubleshooting procedure either given in this paper or in another manual Table 5 No Spectrum possible cause perform check test or troubleshooting procedure no gt X rays o check the X ray source and the sample current no voltage at detector check your detector voltages spectrum definition wrong check spectrum definition cable connection faulty check cable connections preamplifier box detective check preamp box gt section counter device 1n control unit defective contact SP PHOIBOS 31 Troubleshooting Procedure Table 5 No Spectrum possible cause perform check test or troubleshooting procedure no gt and no energy sweep voltage check energy sweep gt section section 7 1 1 1 spectrometer voltages wrong check spectrometer voltages gt section 7 improper adjustment of slit orbit check proper adjustment gt section 4 1 Table 6 Low Intensity perform check test or troubleshooting procedure no gt X ray intensity too low check whether on Ag sample photo current 2 EEE Rb 0c sample 1s dirty sputter until C and O peak in the spectrum dis sample too roug remove roughness wrong analyzer sample distance adjust distance to 40 mm ens system and HSA out of focus check lens and HSA electrodes gt section daa eel and voltages section 7 1 4 M yield to low measure detector supply voltages conversion voltage too low check conver
23. d a slit Both the electron lens system and the slits sizes entrance and exit have an effect on the spread of energies detected at the analyzer detection system The input lens system figure 6 Analyzer vacuum housing PHOIBOS 150 page 9 includes ten lens stages For undisturbed imaging quality the input lens system is grid free The lens stages defines the analysis area and angular acceptance by imaging the sample onto the entrance slit The particles passing through the lens stages and focused onto the input slit S1 of the hemispherical capacitor They are retarded in the lens for subsequent energy analysis in the hemispherical capacitor In addition the lens stage confines the capacitor acceptance angles and area due to the chosen magnification Large Medium Small and by the entrance slit The lens system allows three principal magnifications a Small area mode with high lateral magnification a Medium mode lens and a Large area mode with low magnification see The Lens System on page 11 This magnification can be selected by the SPECS software The angle of acceptance of analysis is constant for Large and Medium mode both for electrons and ions independent of their kinetic energy For the Small mode the acceptance area kept constant Using Large mode it is recommended to use large slits and small pass energies e g 4 20 eV with slit 6 x 20 mm and vice versa for Small e g 30 300 eV with slit diam 1mm In the hemispherica
24. e analyzer parts Table 14 Capacity measurements pF PHOIBOS 100 without PIN housing 1 2 3 4 5 6 7 8 9 10 n 12 connection 1 housing 47 51 52 58 70 51 51 62 201 70 164 0 1 60 36 34 35 28 29 33 47 30 46 0 2 50 38 39 30 30 33 51 33 47 1 3 32 e a 33 32 33 50 38 ae 1 4 58 34 33 34 53 33 5I 0 5 48 37 38 60 36 56 0 6 47 36 51 32 46 1 7 48 53 33 48 1 8 70 39 60 2 9 99 227 1 10 82 n 12 PHOIBOS 37 Power Supply Check and Settings Table 15 Capacity measurements pF PHOIBOS 150 without PIN housing 1 2 3 4 5 6 7 8 9 10 11 12 connection 8 housing 52 53 56 56 54 43 45 58 298 117 259 9 1 70 45 40 40 33 33 37 57 44 54 9 2 57 44 43 34 33 37 57 45 56 8 3 58 44 35 35 37 61 46 57 10 4 59 38 37 39 61 46 57 3 5 42 31 31 51 40 50 3 6 45 33 45 36 45 4 7 45 48 37 45 3 8 64 46 58 2 9 169 382 2 10 132 11 12 If the measured capacities differ substantially from the nominal values please contact SPECS If the capacities have nearly the right values no short circuit inside the spectrometer is most probably Proceed according to the troubleshootin
25. ergy mode the applied voltage to the hemispheres is defined by equation 3 at page 13 In the constant retardation mode Epass is given by Eyass Exin B with the retardation ratio B Bremsfaktor As the trajectories of electrons emitted from the sample are influenced by electrical fields around the sample T1 has a fixed potential it is set to ground potential after switching on the power supply The actual size of the analyzer sampling area DS is in principle given by equation 1 Due to spherical aberration of the input lens however the image in plane of the entrance slit is diffused The degree of diffusion increases for fixed magnification with the input lens acceptance angle This means that also the viewed 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 selectable by the magnification modes to keep the spherical aberration in a well known acceptable 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 broadening or double peaks appear with too large lens acceptance angles Within the PHOIBOS magnification and angular aperture are selectable There are 3 di
26. etic energy scale test 5 2 1 Preparation 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 namely the Au 4f7 and Cu 2p3 peaks energy difference is 848 7 0 1 eV Adjustments Excitation Mg ka X ray power 100W Slit 6x 20 mm Mode LARGE Binding energy range 82 86 eV for the Au 4f7 peak 930 937 eV for the Cu 2p3 peak Step time 100 msec Scan 10 Energy step 25 30 meV Pass energy 8 eV 5 2 2 Check Peak Position Check for proper peak positions corresponding to table 4 Note the error If the peaks offset consistently check if the proper peak position can be achieved by recalibrating the work function software WF If not a kinetic energy calibration is needed please contact SPECS Table4 Calibration Binding Energies for non monochromated Mg Ka X rays Peak Binding energy eV Au 4f5 84 00 0 01 Ag 3dsn 368 27 0 01 Cu 2p 932 66 0 02 5 3 Specification Check 5 3 1 Survey Spectrum of Silver The XPS performance of an energy analyzer is usually determined using a silver sample A cleaned silver sample has to be brought into the vacuum chamber and cleaned by ion sputtering 26 PHOIBOS Specification Check Make the same adjustments as in the overview spectrum of silver enclosed with the Specification Report on the analyzer For example Excitation
27. fferent combinations available The 3 lens settings can be combined with the different possible slit pairs resulting in 3 time number of slit pairs combinations The analyzer sampling areas and input lens acceptance angles for these combinations are given in table 1 Table 1 Analyzer sampling areas and input lens acceptance angles lens lateral magnification max acceptance remarks angle degree Small 10 8 AES ISS Medium 3 2 Large 1 4 be a recommended for point sources b recommended for large area measurements c For large pass energies gt 20eV the peaks become asymmetrically because of overfilling 2 3 2 Hemispherical Analyzer HSA The hemispherical analyzer HSA with a mean radius Rg 100 mm 150 mm performs the spectroscopic energy measurement due to energy dispersion Charged particles entering the HSA 12 PHOIBOS Basic Spectrometer Description through the entrance slit S are deflected to elliptical trajectories by the radial electrical field between the inner hemisphere R and the outer hemisphere Rout The radii of the PHOIBOS hemispheres are 1 25 Ro and 0 75 Ro respectively The entrance slit S and exit plane S are centered on the mean radius Ro R R R 5 oul 150mm EQ 2 For a fixed electrical field gradient only particles with kinetic energies in a certain energy interval are able to pass the full deflection angle from the entrance slit S to the exit p
28. for the exit slit S2 In positioning the feedthrough F2 on figure 6 Analyzer vacuum housing PHOIBOS 150 page 9 to the slit locations the rotary dial is internally fixed near to the right value by a mechanical rest position 4 1 2 Detector Operation For new multiplier CEM please read the start up procedure given for the CEM after bakeout in section 3 5 Normal procedure after bakeout is increasing in small steps 50V within few minutes over a period of 2 hours for start up the detector voltages see Electron Multiplication on page 17 also Common Adry pumped or well trapped diffusion pumped operating environment is desirable A poor vacuum environment can shorten CEM life or change the operating characteristics PHOIBOS 23 System Operation 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 For optimal lifetime operate the detector at the minimum voltage necessary to obtain an usable signal see Electron Multiplication on page 17 4 1 3 Functional Test The detector unit should have been baked out A silver sample with a size not smaller than 5 14 mm should have been transferred into the vacuum chamber The sample has to be cleaned by sputtering The base pressure should be lower than 10 mbar 10 Pa to avoid a damage of the detector by spa
29. 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 type cabinets which utilize silica gel or other solid desiccants to remove moisture have been proven unacceptable 8 2 5 Change Multiplier Multiplier loses its gain ability with operation time It should be changed when a significant degradation in amplification i e intensity is experienced 8 2 5 1 Removing the detector flange Remove the preamplifier connections e Vent the system Open the detector flange let the detector unit slowly down and put it carefully on a table 8 2 5 2 Changing the channeltrons e Note Use dry nitrogen only in order to remove dust or lint Loose the screws keeping the channeltrons in place e Disconnect all cables Note the orientation and dimension of the used unit Remove the multiplier e Put the new multiplier in place e Carefully fasten it with the screws Check the channeltrons on being properly mounted 8 2 5 3 Mounting the detector flange Mount the detector flange in the reverse order 42 PHOIBOS Multiplier e Check that there is no short circuit for all the pins of the detector supply feedthrough to each other and to ground e Pump down e Detector must be baked out at a vacuum pressure lower than 1 10 6 mbar It is bakeable up to 150 C e Check the detector according section 7 2 Figure 13 Detec
30. g procedure given in the manuals If the measured capacities have the correct values a missing contact from the HSA 3000 to the analyzer may be the reason for a faulty spectrum Missing contacts can be found be the following method 7 1 3 1 Check the cable contacts Before this test the correct generation of the spectrometer voltage Ug should be checked see section 7 1 1 2 Mind the safety hints given on page 2 Check also whether the contacts are in good condition Since the plug is a movable part which is frequently plugged and unplugged it is able to become defective In most cases of contact failures the plug is the reason 7 1 4 Check HSA voltages Check whether the electrode voltages are present at the female contacts of the spectrometer plugs Write down the measured voltages for a given kinetic energy and a given pass energy note WF in software in table 16 Send this table to SPECS If the measured values are correct the plug is o k 38 PHOIBOS Control Unit Check Table 16 Voltages to ground for all modi Exin E Slit pair WF paas voltages PIN Large Medium Small TI T2 T3 T4 T5 T6 T7 T8 T9 T10 inner hemisphere sO CO NY Alaja BY BW N l outer hemisphere not used Connect the spectrometer plug and start a spectrum If no spectrum is obtained the faulty contact is most probably inside the spectrometer
31. he sample plane on the HSA entrance plane define the analyzed sample area and the accepted solid angle on a sample accelerate decelerate the particles with the observed energy to the pass energy By 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 If S1 has the dimension D1 then by theory the imaged area of the sample has the dimension DS with DS D1 M EO I For the PHOIBOS the magnification of the lens stage is selectable to be M 10 3 or 1 in the Small Medium and Large lens mode The magnification is changed electrically by connecting appropriate voltages to the lens electrodes The voltages are a function of the spectrometer voltage Ug which depend on the particle kinetic energy being analyzed and the analyzer pass energy see Hemispherical Analyzer HSA on page 12 Up is negative for electrons and positive for ions PHOIBOS 11 Description In the lens stage the particles passing through an intermediate image and will focused onto the input slit S1 of the hemispherical capacitor figure 7 At S1 the particles have been retarded by the energy difference between the nominal particle kinetic energy E in and the nominal pass energy Epass The PHOIBOS can operate in Constant Retardation Ratio CRR and Constant Analyzer Energy CAE modes In constant analyzer en
32. l Typical use of the PHOIBOS analyzer is in photoelectron spectroscopy XPS SSXPS UPS Auger electron spectroscopy AES SAM and ion scattering spectroscopy ISS The PHOIBOS is bakeable up to 250 C after remove of few connections for the detector and lens supply PHOIBOS 1 Introduction safety Hints Before any electric or electronic operations please consult SPECS Safety Instructions and follow them strictly Some adjustments which might have to be carried out according to this manual are hazardous At each such a point is there a warning label Attention The tests described in the following have to be performed on the electronic unit with its cover removed Hazardous voltage are present therefore only persons with the appropriate training are allowed to do the job Make all trimmer settings only with a special insulated trimmer screwdriver PHOIBOS Chapter Description 2 1 System Description The PHOIBOS analyzer consists of the following mechanical parts e analyzer housing e internal u metal shielding lens system e hemispherical analyzer e multichannel MCD or single detector SCD e Slit Orbit mechanism The electronics of the PHOIBOS consists of power supply for PHOIBOS analyzer HSA 3000 e preamplifier cables with Filter Unit and series resistor for ech channel R 20 MQ divided by the number of channels fixed with the cable The HSA 3000 unit
33. l capacitor the particles passing through the entrance slit S1 are focused 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 central trajectory possess the nominal pass energy They are focused to the central radial position As the radial position of the slit image increases for fixed capacitor potential with the particle energy particles with higher kinetic energy are focused further outside and particles with lower energy are focused further inside in plane S2 This offers the possibility for multichannel detection with simultaneous recording of an energy band around the nominal pass energy The particles passing through the capacitor output plane S2 are accelerated onto the detector system C In the multichannel detector the particles are first multiplied using a multiplier arrangement Each channel is connected to a separate preamplifier mounted outside the vacuum The preamplifiers are read out by a Multi Channel Detector MCD counter interface of the SPECS data acquisition software The PHOIBOS system can operate in a Constant Retardation Ratio CRR or in a Constant Analyzer Energy CAE mode PHOIBOS 7 Description VIEWPORT FOR ALIGNMENT DN350CF VARIABLE SLIT DRIVE 575 DN100CF or specified by customer s 4 NSAMPLE Figure 5 Analyzer vacuum housing PHOIBOS 100
34. lane S5 Particles with higher kinetic energy approach the outer hemisphere whereas particles with lower kinetic energy are deflected toward the inner hemisphere Those particles which enter the HSA normal to S and move through the hemispheres on the central circular trajectory have the nominal pass energy Epass Epass 9 kAV EQ 3 where q is the charge of the particle the potential difference AV Vout Vin applied to the hemispheres k is the calibration constant k oo Rinkou _ 0 9375 EQ 4 CORR eR EQ 4 out These particles reach S5 at the nominal radial position Ro If the HSA accepts the half angle o in the dispersion direction the HSA resolution or FWHM full width at half maximum of the transmitted line AE is given by AE S E IR EQ 5 pass 4 8 where S S 5 2 This value is an analyzer constant There are additional contributions to the line width observed in the spectrum For photoemission lines the main additional contributions are a inherent line width of the atomic level ABjeye e g O 1s C 1s b natural line width of the characteristic radiation used for excitation AE photo e g Mg Ka Al Ko The observed total FWHM o a is given by the convolution of the single FWHMs e g for gaussian line witdhs FWHM total level AE AE AES oto V 2 AE EQ 6 FWHM otaj is usually specified using a sputter cleaned silver sample and recording the Ag 3d level after linear backgr
35. led to minimize the distance between the X ray source and the sample The distance between the sample and the lens T1 must be fixed to the working distance of 40 mm None of these three parts should have mechanical contact to each other Check the resistivity of the pins of the HSA 12 pin figure 3 and detector feedthroughs figure 4 to ground and to each other to exclude short circuits This is especially important to check short circuit between ground plate and cathode The resistivity has to be infinite for all cases except between the cathode and anode contacts of the CEM which should be higher than 20 MQ internal resistance The performance of the MCD is decreasing with the time exposed to air Try to minimize the time between its mounting and evacuating 3 5 Baking Out The vacuum chamber has to be baked out to get good UHV in a reasonable time The temperature during the bake out should be up to 150 C A reference thermocouple for the temperature measurement should be attached to the MCD flange F5 in figure 6 Before baking out HSA cable e preamplifier with connection cables to the flange must be removed see figure 1 The preamplifier can be removed by release one screw Then the complete unit should be stored for the time of bakeout A bakeout time between 12 hours and 24 hours first time is recommended The interior parts of the PHOIBOS will cool down significantly slower than the housing The multiplier will degas
36. mode is mainly used in XPS and UPS when detailed information is needed and the resolution should not be dependent on the energy Besides when E is a constant by measuring the same peak with a different pass energy it follows that LE EQ 13 2 3 3 HSA 3000 Voltage Ranges All units provide the detection of electron energies between 0 3000 eV with minimum step widths of 13 meV The unit can be upgraded by an additional voltage modules Hi RES or Super Hi Res allowing 0 300 eV scans with minimum step widths of 1 3 meV 0 2 meV Super Hi RES only within a range 50 eV This modules based on high resolution EELS technology for fine scans with step widths 0 2meV and overall ripples below 1 meV for the Super Hi RES Table 2 Voltage Ranges Standard Hi RES and Super Hi RES supplied by range resolution possible step with lens potentials E in HSA 3000 standard 0 3000 V 18 Bit 13 mV lens potentials E HSA 3000 Hi RES 0 300 V 18 Bit lt 1 3mV lens potentials E HSA 3000 Super Hi RES 0 300 V 18 Bit within a range 0 2mV of max 50 eV Epass HSA 3000 0 300 V 18 Bit lt 13 mV 2 3 4 Slit Orbit Mechanism In the HSA a Slit Orbit mechanism is fitted as an optional feature for variable choice of slit pairs The standard analyzer is build with one pair of slits chosen by the customer The Slit Orbit mechanism is configured for example with following pairs of slits Table 3 Slit Pairs
37. n matrix is a high gain device for detecting energetic particles such as electron and ions or radiation The channeltron consist 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 8 2 4 Handling e Shipping containers should be opened only under clean dust free conditions PHOIBOS 41 Spare Parts 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 degreased tools fabricated from stainless steel teflon PTFE or other UHV compatible materials 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 8 2 4 1 Storage Multiplier Due to the hygroscopic nature of the doped lead glass it is important that the channeltrons are stored properly Warning The shipping containers are not suitable for storage periods exceeding the delivery time Upon delivery to the customer s facility channeltron must be transferred to a suitable long term storage medium The most effective long term storage condition for the channeltron is a clean oil
38. nds 2 3 5 4 Conversion Voltage The conversion voltage produced in the HSA 3000 determines the conversion energy Econy dUcony EQ 18 of the charged particles impinging the CEM The proper conversion voltage has two requirements which must be simultaneously fulfilled the particles energy should be suitable for maximum yield of secondary electron emission at the impact on the CEM wall This for electrons is roughly in the energy range between 100 and 800 eV e For ions the yield increases with the kinetic energy roughly up to 10 keV Standard settings are forelectrons Ucony 128 V conv E kin lt or equal 128V e for ions Ucony 3 KV PHOIBOS 19 Description 2 4 Work Function The basic energetic properties are shown in figure 10 for the example of the measurement of photoelectrons sample spectrometer E Exin kin vacuurn level hv Wf WI ost sample fermi BEEN oo A Ebin EE core i levels Figure 10 Energy scheme in case of photo electron 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 yin hvy Exin gt We EQ 19 The energy E see figure 10 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
39. ntroduce the lens system into the vacuum chamber flange very slowly Do not use any force 10 During the introduction check all other components in the vacuum chamber because of possible mechanical damage 11 Adjust the analyzer at the vacuum chamber flange by the stay bolts PHOIBOS 45 Appendix 12 Check the working distance of the analyzer 13 Fix the analyzer at the vacuum system flange with the delivered screws washers and nuts 14 Do not release the lifting gear up to the point where the analyzer is supported by an additional supporting post 15 Check the mechanical stability of the supporting post and the system rack 16 Release the lifting gear 17 Evacuate the chamber to a pressure of below 10 hPa and bake out see Baking Out on page 22 18 Check the vacuum before and after bakeout 19 After bake out check for no short circuits between all not grounded pins figure 3 and figure 4 at page 6 20 Connect the analyzer as described in the analyzer manual 21 Before operating the analyzer wait for complete cool down 1 day recommended 46 PHOIBOS Chapter L F List of Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure RW N e O o N nm 10 12 13 Connection scheme of the PHOIBOS SCD components Connection scheme of the PHOIBOS MCD components Schematics of the 12 pin HSA feedthrough Detector schematic connection
40. ound substraction For Mg Ka excitation the resolution at low HSA pass energies for the Ag 3dsj level is found to be FWHM ugra 0 8eV EQ 7 In most practical work a resolution of 0 9 eV is usually sufficient for high resolution investigations For higher instrumental resolution it is possible to use monochromatized X radiation for excitation e g mainly monochromatized Al Ka radiation Then the background is usually taken at 10 eV on the PHOIBOS 13 Description high kinetic energy side of the Ag 3ds level For monochromatized Al Ka radiation and for the Ag 3ds5 2 level the extreme resolution is found to be FWHMaxtreme 0 44 eV EQ 8 For attaining the extreme resolution of 0 44 eV FWHM X ray has to be strongly restricted by utilizing only a small part of the X ray monochromator at the expense of a strong loss in intensity In practical work a resolution of 0 65eV is usually sufficient for high resolution investigations with monochromatized Al Ka excitation For monochromatized radiation FWHM tq is sometimes specified recording the Si 2p3 2 level instead of the Ag 3d5 2 level which results in smaller values of FWHMoxtreme due to the narrower inherent line width of the Si 2p level The integral signal intensity I of the measured particles the area under the peak with a background subtracted is proportional to product of the accepted solid angle Os the accepted sample area Ag and the HSA resolution AE n 2 E E
41. rks For special reasons e g for depth profiling with noble gas ions operation up to 4 107 mbar 4 10 Pa is allowed Set the software to XPS Ej 800 eV start short measure voltage will stay at the end energy the pass energy to 20 0 eV largest slit and the X ray source to 100 W Adjust the detector voltage to the value corresponding to the Specification Report of the analyzer nominal value is 2400 V Use the SpecsLab mode Detector Sweep and set start end step and dwelltime parameter for this procedure Check with Validate the run time for this special measurement Measure a wide energy XPS spectrum scanning the kinetic energy of the particles from 0 to 1 5 keV e g with an energy step of 500meV and pass energy of 20 0 eV In a first rough test without careful adjustment one should get 10 cps at the Ag 3ds peak using 100 W Mg Ka X ray source power and a clean silver sample 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 Check also whether the intensity of the C and O peaks are smaller than 2 of the Ag 3ds peak Otherwise the sample should be sputtered once more 4 2 Quick Operation Check vacuum conditions Check sample Switch on the analyzer supply HSA 3000 Start the acquisition SpecsLab and control source window software Set detector voltage and other parame
42. see Connection Check for the HSA Electrodes on page 37 If something like a spectrum is obtained the missing contact can be found by connecting the electrodes one by one to a different potential ground or a neighboring electrode potential in the HSA 3000 and taking a spectrum every time If after an electrode has been switched the spectrum does not change its shape the faulty electrode contact has been found 7 1 5 Preamplifier Check 7 1 5 1 Discriminator Check the discriminator threshold using the noise of the signal within one spectrum The square root of the signal should be equal to the RMS root mean square of the noise at this energy Use the fixed mode of the acquisition software to estimate the noise at constant kinetic energy for the acquired signal and compare with the square root of the signal counts not cps Change the discriminator threshold by the potentiometer at the preamplifier box and check again If both values similar the discriminator threshold has the right value 7 1 5 2 Amplifier Check Set the detector voltage to zero Mind the safety hints given on page 2 Disconnect the preamplifier from the detector flange Upon light touching with a piece of wire to each pin hole of the preamplifier pin connector signal must be observed number of channels times on the monitor PHOIBOS 39 Power Supply Check and Settings If signal is observed a smaller number of times not all channels of the
43. setup and feedthrough pin booking view from atmospheric side Analyzer vacuum housing PHOIBOS 100 Analyzer vacuum housing PHOIBOS 150 Main components of the spectrometer Analyzer Voltage Principle Detector sweep Count rate vs voltage Energy scheme in case of photo electron spectroscopy XPS on silver wide scan PHOIBOS 150 SCD XPS on silver Ag 3d PHOIBOS 150 SCD Detector unit 9 channel 10 11 18 20 28 29 43 PHOIBOS PHOIBOS Chapter LT List of Tables Table 1 Table 3 Table 2 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 10 Table 11 Table 12 Table 13 Table 14 Table 15 Table 16 Analyzer sampling areas and input lens acceptance angles Slit Pairs Voltage Ranges Standard Hi RES and Super Hi RES Calibration Binding Energies for non monochromated Mg Ka X rays No Spectrum Low Intensity Low Energy Resolution Peaks Shifted Equally Peaks Shifted Differently Intensity Fluctuations High Background Signal Noisy Spectrum Wrong analyzed area in Small Medium Large mode Capacity measurements pF PHOIBOS 100 Capacity measurements pF PHOIBOS 150 Voltages to ground for all modi 12 15 15 26 31 32 32 33 33 33 34 34 34 37 38 39 PHOIBOS PHOIBOS Chapter Index A D I Amplifier Check 39 Detector sweep 18 Intensity Fluctuations 33 Analyzer Test 25 Detector unit 9 channel 43 Analyzer vacuum housing 8 9 Aperture Drive 23
44. sion voltage MCD preamplifier setting changed check preamp settings gt section 2 3 5 some channels of the preamplifier unit check operation of the preamplifier by use of a defective separated channel mode of the control unit or gt section 7 1 5 magnetic fields 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 mechanical wrong adjustments like Open analyzer system and grids damaged lenses misaligned if all other kinds of faults can be excluded spheres shifted MCD shifted improper adjustment o check proper adjustment section 4 1 Slit Orbit mechanism Table 7 Low Energy Resolution possible cause perform check test or troubleshooting procedure no gt chemical peak broadening sputter cleaning ateral inhomogeneous charging of the use charge compensation by means of electron sample flood gun 32 PHOIBOS Possible Problems Table 7 Low Energy Resolution possible cause perform check test or troubleshooting procedure no gt noise or and ripple on the following voltages the ground connection of all the power sup sample spectrometer voltage Uo plies section 3 3 detector voltage electrode voltages of the analyzer magnetic fields 1n the region of the measure magnetic field spheres preamplifier setting changed check preamp setting gt section 2 3 5 ens sy
45. software validate the values to the nearest allowed values 2 3 5 3 Electron Multiplication A Single Channel Electron Multiplier channeltron or CEM is a high gain device for detecting energetic particles such as electron and ions or radiation The CEM consist 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 By the impact of charged particle secondary electrons are released from the CEM wall These electrons are accelerated by the high voltage connected to the CEM and release additional secondary 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 incident 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 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 PHOIBOS 17 Description Figure 9 necessary 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 C
46. stem and HSA out of focus check lens and HSA electrodes gt section and voltages section 7 1 4 detector supply voltage wrong 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 Table 8 Peaks Shifted Equally possible cause perform check test or troubleshooting procedure no gt work function setting wrong eck the work function setting sample charging eck the sample ground connection Use external electron flood gun to compensate for the charging voltages of the different pass energies sphere are wrong the peaks are shifted Check HSA voltages gt section 7 1 3 Zero point drift of the spectrometer volt check zero point of HSA 5000 age section 7 1 1 3 Table 9 Peaks Shifted Differently possible cause perform check test or troubleshooting procedure no gt wrong amplification factor check Up A section 7 1 1 section 7 1 1 2 Table 10 Intensity Fluctuations possible cause perform check test or troubleshooting procedure no gt malfunction of counter board gt control unit manua PHOIBOS 33 Troubleshooting Procedure Table 10 Intensity Fluctuations possible cause perform check test or troubleshooting procedure no gt one lens electrode not connected un a spectrum with high speed
47. ter in the source window Switch on the excitation source Set the scan parameter for the region Press measure Sese D GO ci centur Er Dex Save the results 10 Switch off the units 24 PHOIBOS Chapter Analyzer Test 5 1 Independence of peak position with pass energy Transfer a silver sample into the system Warm up your electronic for at least 1 hour Adjustments Excitation Mg Ka X ray power 100W Slit 6x 20mm Mode LARGE Binding energy range 365 375 eV Scan 10 Step time 100 msec Energy step 25 30 meV Pass energy 15eV Run a spectrum Set pass energy of about 5 eV Repeat the measurement Compare the spectra If the voltages fit to the spectrometer the peak maxima of both spectra have to point exactly to the same energy The peaks positions of both spectra should not differ by more than 100 meV For symmetrical peaks the peak position is independent of E This is not true for Auger electron peaks since the peaks are intrinsically asymmetrical pass If the peak positions differ a calibration might be needed for the hemisphere voltages Ugg Outer Hemisphere The voltage set in the HSA 3000 The calibration should be done by vary Ug using the potentiometer P16 in the HSA 3000 To use the potentiometer the rear panel of the HSA 3000 has to be opened Usually no calibration should be necessary For more detailed information please contact SPECS support PHOIBOS 25 Analyzer Test 5 2 Kin
48. tor unit 9 channel PHOIBOS 43 Spare Parts 44 PHOIBOS Chapter Appendix 9 1 Unpacking All analyzers and associated electronics are carefully packed before leaving the factory Please examine packages for damage If damage is suspected contact SPECS and always retain packing inspection After examination the analyzer should stay in its protective packaging until it can be bolt directly onto the system Take great care when unpacking to prevent damage Do not rest the analyzer on ceramic feedtroughs or the viewport Handle parts on the vacuum side of the flange seals using normal UHV protection i e wear cloves and use clean non magnetic tools 9 2 Vacuum Installation 1 Open the transport box carefully Check the shock and tilt sensors If any sensor is discoloured please inform SPECS immediately and wait for further instructions Carefully lift the analyzer out of the box Because of the analyzer weight of 80kg SPECS recommend to use a lifting gear The hooks at the analyzer housing may be of help 4 Keep the analyzer in a horizontal and stable position 5 Remove the lens protection housing from the analyzer mounting flange Do not touch any vacuum parts without gloves 6 Fix the two delivered stay bolts at the analyzer mounting flange T 8 9 Insert a new DN100CF copper gasket into the vacuum chamber flange Center the analyzer mounting flange above the vacuum chamber flange I
49. tra and achieved values differ essentially from the ones of the Specification Report on the analyzer it might be that the sample should be sputtered some more the sample and X ray source positions should be optimized or a HSA 3000 calibration might be needed See although section 6 In many cases it is helpful to know the intensities signals and accompanying FWHMs at different values of pass energy For such purpose the measurements described above have to be made at pass energies nearest to the values of 2 5 10 20 and 50eV for slit 6 x 20 mm and up to 200 eV for PHOIBOS 27 Analyzer Test diam 1mm slit The step time or number of scans should be adapted 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 step time than for high pass energies This gives comparable counting statistics for all measurements 5 4 Typical Spectra aputtered silver sample SPECS Customer Service Sage 150 rz trfin phnihnre silver nverviee 1200 1000 P 800 x f 600 4 d b T E 400 4 2UU 4 T T T T T u 200 400 600 5800 1000 1200 Kinetic Energy eV Mq Method Lens start End step scans Dwell Pass Date Time Tag ai xes r 100 00 1300 00 1 00 1 9 10 20 20 apr 1888 21 48 00 overview SPECS 24 Apr 1333 48 50 06 Figure 11 XPS on silver wide scan PHOIBOS 150 SCD
50. u 4f7 and Cu 2p3 peaks energy difference is 848 7 0 1 eV Adjustments Excitation Mg ka X ray power 100W Bin energy range 81 87eV for the Au 4f7 peak 930 936 eV for the Cu 2p3 peak Step time 50 msec 36 PHOIBOS Control Unit Check Energy step 25 30 meV Pass energy 30eV Run spectra of both peaks Measure the distance between the peak maxima of gold and copper If the value found differs from 848 7 eV please inform SPECS Of course after every adjustment of the analyzer or replacement of modules HSA 3000 a new spectrum has to be taken to control Note Please taking into account the software set workfunction and possible charges on the sample 7 1 3 Connection Check for the HSA Electrodes Check the electrode connection with the electrical feedtrough For this check a capacity measurement must be used Best way to check is to measure the capacities between all pins of the feedtrough of the analyzer see figure 3 Schematics of the 12 pin HSA feedthrough page 6 Switch off the HSA 3000 and remove the connector to the HSA electrodes Mind the safety hints given on page 2 The capacities measured on the HSA and lens electrodes under UHV conditions in table 14 respectively table 15 are only for information Some differences across the meter should be taken into consideration when checking the values Comparable absolute values but correct ratios between the values shows correct connection to th
51. ut one year at 40 hours operation per week Multiplier Plateau SPECS Customer Service performed by a detector sweep Sage 150 stefan phoibos Artentor sween 60 Multiplier Plateau 50 4 620 mm Ep 30 eV 40 d P B LARGE Dwell Tine 1 s 30 4 Ek 800 eV i Es u D u 20 4 s 4 10 4 D T T T T T 500 1000 1500 2000 2500 Kinetic Energy eV Mg Method Lens Start End Step Scans Dwell Pass Tate Time Tag alles mom 000 007 zu oo i 1 00 2020 Apr 1909 16 51 00 SPECS 22 Apr 1999 13 50 34 Detector sweep Count rate vs voltage The sensitivity of the preamplifier channels can be varied using a discriminator threshold potentiometer located at the outer face of the MCD preamplifier housing the value is factory preset recommended discriminator voltage see section 7 1 5 1 18 PHOIBOS Basic Spectrometer Description 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 107 after which point increasing the voltage further will cause the eventual breakdown of the CEM With an proper configured oscilloscope i e impedance 50 Ohm the necessary pulse height can be checked For the PHOIBOS analyzer an input of one electron the CEM responds by producing an output pulse of charge which contain at least 107 electrons and which lasts for approximately 10 nanoseco
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