Basic XPS Information Section

The Basic XPS Information Section provides fundamental XPS spectra, BE values, FWHM values, BE tables, overlays of key spectra, histograms and a table of XPS parameters.
The Advanced XPS Information Section is a collection of additional spectra, overlays of spectra, peak-fit advice, data collection guidance, material info,
common contaminants, degradation during analysis, auto-oxidation, gas capture study, valence band spectra, Auger spectra, and more.
Published literature references, and website links are summarized at the end of the advanced section.
→  Periodic Table – HomePage                    XPS Database of Polymers                 → Six (6) BE Tables


Germanium (Ge)

 

Germanium is a trace component in
Sphalerite, ZnS		 Germanium – Geo Germanite – Ag8GeS6

 

  Page Index
  • Expert Knowledge & Explanations


Germanium (Geo) Metalloid
Peak-fits, BEs, FWHMs, and Peak Labels

  .
Germanium (Geo) Metalloid
Ge (3d) Spectrum – raw spectrum 		 Germanium (Geo) Metalloid
Peak-fit of Ge (3d) Spectrum (w/o asymm)
→  Periodic Table – HomePage  
Germanium (Geo) Metalloid
Ge (2p) Spectrum
 Germanium (Geo) Metalloid
Ge (2p3/2) peak-fit

 

→  Periodic Table – HomePage  
Germanium (Geo) Metalloid
Ge (3s) Spectrum		 Germanium (Geo) Metalloid
Ge (3p) Spectrum

 

Survey Spectrum of Germanium (Geo) Metalloid
with Peaks Integrated, Assigned and Labelled

→  Periodic Table 

XPS Signals for Germanium, (Geo) Metalloid

Spin-Orbit Term,  BE (eV) Value, and Scofield σ for Aluminum Kα X-rays (1486 eV, 8.33 Ang)

Overlaps Spin-Orbit Term BE (eV) Value Scofield σ from 1486 eV X-rays IMFP (TPP-2M) in Å
  Ge (2p1/2) 1249 12.52 8.2
  Ge (2p3/2) 1217 24.15 8.9
  Ge (3s) 181 1.23 27.4
Al (2s) overlaps Ge (3p) 122 2.39 28.4
W (4f) overlaps Ge (3d) 29.13 1.42 29.9

σ:  abbreviation for the term Scofield Photoionization Cross-Section which is used with IMFP and TF to generate RSFs and atom% quantitation

 

Auger Peaks

 

 Intrinsic Plasmon Peak:  ~16eV above peak max
Expected Bandgap for GeO2: 4.6 eV

*Scofield Cross-Section (σ) for C (1s) = 1.0

→  Periodic Table 

 

Ge (3s) and (3p) Spectra from Geo Metalloid
Fresh exposed bulk produced by extensive Ar+ ion etching

Ge (3s) Ge (3p)
   

→  Periodic Table – HomePage  

 

Valence Band Spectrum from Germanium, Geo Metalloid
 Fresh exposed bulk produced by extensive Ar+ ion etching

 

 

Plasmon Peaks from Geo Metalloid
 Fresh exposed bulk produced by extensive Ar+ ion etching

Ge (3d) – Extended Range Spectrum Ge (3d) – Extended Range Spectrum – Vertically Zoomed
→  Periodic Table 

 

Ge (LMM) Auger Peaks from Germanium, Geo Metalloid
 Fresh exposed bulk produced by extensive Ar+ ion etching
Geo Metalloid – LMM peak-fit Geo Metalloid – Full Range

 

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

Artefacts Caused by Argon Ion Etching

Germanium Carbide(s)

can form when ion etched Reactive Surfaces capture
Residual UHV Gases (CO, H2O, CH4 etc)

Argon Trapped in Geo

can form when Argon Ions are used
to removed surface contamination
 

 

Side-by-Side Comparison of
Ge Native Oxide & Germanium Oxide, GeO2
Peak-fits, BEs, FWHMs, and Peak Labels
Ge Native Oxide GeO2
Ge (3d) from Ge Native Oxide
Flood Gun OFF
As-Measured, C (1s) at 285.1 eV 		 Ge (3d) from GeO2 – 3 mm pressed pellet
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 

 
→  Periodic Table 
   
Ge Native Oxide GeO2
C (1s) from Ge Native Oxide
on Germanium
As-Measured, C (1s) at 285.1 eV
Flood Gun OFF

C (1s) from GeO2 – 3 mm pressed pellet
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV
Ge Auger Peaks Overlap C (1s)

 

→  Periodic Table 
  . 
Ge Native Oxide GeO2
O (1s) from Ge Native Oxide
on Germanium
As-Measured, C (1s) at 285.1 eV (Flood Gun OFF)

O (1s) from GeO2 – 3 mm pressed pellet
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 

 
→  Periodic Table

 
.
Ge Native Oxide GeO2
Ge (LMM) Auger Peaks from Ge Native Oxide
on Germanium
As-Measured, C (1s) at 285.1 eV (Flood Gun OFF)

Ge (LMM) Auger Peaks from GeO2 – 3 mm pressed pellet
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 

 

 


Survey Spectrum of Germanium (Ge) Native Oxide
with Peaks Integrated, Assigned and Labelled

→  Periodic Table 

 

 

Survey Spectrum of Germanium Oxide (GeO2)
with Peaks Integrated, Assigned and Labelled

→  Periodic Table  

 

Overlays of Ge (3d) Spectra for
Ge Native Oxide and GeO2

Caution: BEs from Grounded Native Oxides can be Misleading if Flood Gun is ON

 Overlay of Geo metalloid and Ge Native Oxide – Ge (3d)
Native Oxide C (1s) = 285.1 eV (Flood gun OFF)
BE scale of Native Oxide shifted by 0.7 eV to align metal peaks
  Overlay of Geo metalloid and GeO2 – Ge (3d)
Pure Oxide C (1s) = 285.0 eV
Chemical Shift: 3.6
→  Periodic Table  Copyright ©:  The XPS Library 

 

Overlay of Ge (3d)
Geo Metalloid, Ge Native Oxide, & GeO2  

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

Valence Band Spectra
Geo, GeO2 

Geo
Ion etched clean		 GeO2 – pressed pellet
Flood gun is ON,  Charge referenced so C (1s) = 285.0 eV

Overlay of Valence Band Spectra 
for Geo metalloid and GeO2

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

Germanium – Man-made Chemical Compounds

 
ZnGeP2 – Zinc germanium phosphide
Non-Linear Optical Crystal for Lasers		 Germanium Sulfide – GeS2 Germanium Nitride – Ge3N4 Target Germanium Oxide – GeO2

→  Periodic Table 

 

 

Six (6) Chemical State Tables of Ge (3d5/2) BEs

 

  • The XPS Library Spectra-Base
  • PHI Handbook
  • Thermo-Scientific Website
  • XPSfitting Website
  • Techdb Website
  • NIST Website

→  Periodic Table 

 

Notes of Caution when using Published BEs and BE Tables from Insulators and Conductors:

  • Accuracy of Published BEs
    • The accuracy depends on the calibration BEs used to calibrate the energy scale of the instrument.  Cu (2p3) BE can vary from 932.2 to 932.8 eV for old publications 
    • Different authors use different BEs for the C (1s) BE of the hydrocarbons found in adventitious carbon that appears on all materials and samples.  From 284.2 to 285.3 eV
    • The accuracy depends on when the authors last checked or adjusted their energy scale to produce the expected calibration BEs
  • Worldwide Differences in Energy Scale Calibrations
    • For various reasons authors still use older energy scale calibrations 
    • Some authors still adjust their energy scale so Cu (3d5/2) appears at 932.2 eV or 932.8 eV because this is what the maker taught them
    • This range causes BEs in the higher BE end to be larger than expected 
    • This variation increases significantly above 600 eV BE
  • Charge Compensation
    • Samples that behave as true insulators normally require the use of a charge neutralizer (electron flood gun with or without Ar+ ions) so that the measured chemical state spectra can be produced without peak-shape distortions or sloping tails on the low BE side of the peak envelop. 
    • Floating all samples (conductive, semi-conductive, and non-conductive) and always using the electron flood gun is considered to produce more reliable BEs and is recommended.
  • Charge Referencing Methods for Insulators
    • Charge referencing is a common method, but it can produce results that are less reliable.
    • When an electron flood gun is used, the BE scale will usually shift to lower BE values by 0.01 to 5.0 eV depending on your voltage setting. Normally, to correct for this flood gun induced shift, the BE of the hydrocarbon C (1s) peak maximum from adventitious carbon is used to correct for the charge induced shift.
    • The hydrocarbon peak is normally the largest peak at the lowest BE. 
    • Depending on your preference or training, the C (1s) BE assigned to this hydrocarbon peak varies from 284.8 to 285.0 eV.  Other BEs can be as low as 284.2 eV or as high as 285.3 eV
    • Native oxides that still show the pure metal can suffer differential charging that causes the C (1s) and the O (1s) and the Metal Oxide BE to be larger
    • When using the electron flood gun, the instrument operator should adjust the voltage and the XY position of the electron flood gun to produce peaks from a strong XPS signal (eg O (1s) or C (1s) having the most narrow FWHM and the lowest experimentally measured BE. 

→  Periodic Table 

Table #1

Ge (3d5/2) Chemical State BEs from:  “The XPS Library Spectra-Base”

C (1s) BE = 285.0 eV for TXL BEs
and C (1s) BE = 284.8 eV for NIST BEs

Element Atomic # Compound As-Measured by TXL or NIST Average BE Largest BE Hydrocarbon C (1s) BE  Source
Ga 31 GaInAs 17.5 eV 18.2 eV 285.0 eV The XPS Library
Ga 31 GaSe 17.6 eV   285.0 eV The XPS Library
Ga 31 Ga – element 18.6 eV   285.0 eV The XPS Library
Ga 31 GaAs (N*16) 18.6 eV 19.7 eV 284.8 eV Avg BE – NIST
Ga 31 GaSb 18.6 eV 19.1 eV 285.0 eV The XPS Library
Ga 31 GaSb (N*4) 18.9 eV 19.0 eV 284.8 eV Avg BE – NIST
Ga 31 GaAs 19.1 eV 19.7 eV 285.0 eV The XPS Library
Ga 31 GaP (N*5) 19.2 ev 19.9 eV 284.8 eV Avg BE – NIST
Ga 31 GaN (N*2) 19.5 eV 19.7 eV 284.8 eV Avg BE – NIST
Ga 31 GaAlAs 19.6 eV   285.0 eV The XPS Library
Ga 31 Ga2Se3 (N*2) 19.7 eV 19.9 eV 284.8 eV Avg BE – NIST
Ga 31 GaP 19.7 eV 20.0 eV 285.0 eV The XPS Library
Ga 31 GaN 20.0 eV   285.0 eV The XPS Library
Ga 31 Ga2O3 (N*5) 20.2 eV 20.7 eV 284.8 eV Avg BE – NIST
Ga 31 Ga-2O3 21.3 eV   285.0 eV The XPS Library
Ga 31 Ga-(OH)3     285.0 eV The XPS Library
Ga 31 Ga-2O     285.0 eV The XPS Library
Ga 31 Ga-Cl3     285.0 eV The XPS Library
Ga 31 Ga-CO3     285.0 eV The XPS Library
Ga 31 Ga-F3     285.0 eV The XPS Library
Ga 31 Ga-S     285.0 eV The XPS Library

Charge Referencing Notes

  • (N*number) identifies the number of NIST BEs that were averaged to produce the BE in the middle column.
  • The XPS Library uses Binding Energy Scale Calibration with Cu (2p3/2) BE = 932.62 eV and Au (4f7/2) BE = 83.98 eV.  BE (eV) Uncertainty Range:  +/- 0.2 eV
  • Charge Referencing of insulators is defined such that the Adventitious Hydrocarbon C (1s) BE (eV) = 285.0 eV.  NIST uses C (1s) BE = 284.8 eV 
  • Note:   Ion etching removes adventitious carbon, implants Ar (+), changes conductivity of surface, and degrades chemistry of various chemical states.
  • Note:  Ion Etching changes BE of C (1s) hydrocarbon peak.
  • TXL – abbreviation for: “The XPS Library” (https://xpslibrary.com).  NIST:  National Institute for Science and Technology (in USA)

→  Periodic Table 

Table #2

Ge (3d5/2) Chemical State BEs from:  “PHI Handbook”

C (1s) BE = 284.8 eV

→  Periodic Table 

Copyright ©:  Ulvac-PHI

Table #3

Ge (3d5/2) Chemical State BEs from:  “Thermo-Scientific” Website

C (1s) BE = 284.8 eV

Chemical state Binding energy (eV),
Ge (2p3)		 Binding Energy (eV),
Ge (3d)
Ge elemental 1217.3 29.3
GeO 1218.0 30.9
GeO2 1220.2 32.5

→  Periodic Table 

Copyright ©:  Thermo Scientific 

Table #4

Ge (3d5/2) Chemical State BEs from:  “XPSfitting” Website

Chemical State BE Table derived by Averaging BEs in the NIST XPS database of BEs
C (1s) BE = 284.8 eV

→  Periodic Table 

Copyright ©:  Mark Beisinger

Table #5

Ge (3d5/2) Chemical State BEs from:  “Techdb.podzone.net” Website

 

XPS Spectra – Chemical Shift | Binding Energy
C (1s) BE = 284.6 eV

XPS(X線光電子分光法)スペクトル 化学状態 化学シフト ケミカルシフト

Element Level Compound B.E.(eV) min   max
Ge 3d Ge 29.4 ±0.2 29.2 ～ 29.5
Ge 3d GeAs2 29.8 ±0.3 29.5 ～ 30.0
Ge 3d GeTe 29.8 ±0.2 29.6 ～ 30.0
Ge 3d Sulfides 29.9 ±0.5 29.4 ～ 30.4
Ge 3d GeTe3As2 30.0 ±0.3 29.7 ～ 30.2
Ge 3d GeTe2 30.1 ±0.3 29.8 ～ 30.3
Ge 3d GeS2TeAs2 30.3 ±0.3 30.0 ～ 30.5
Ge 3d GeS3As 30.4 ±0.3 30.1 ～ 30.7
Ge 3d GeSe 30.9 ±0.3 30.6 ～ 31.2
Ge 3d GeSe2 31.0 ±0.3 30.7 ～ 31.3
Ge 3d GeO2 32.5 ±0.3 32.2 ～ 32.8

 

→  Periodic Table 

 


Histograms of NIST BEs for Ge (3d5/2) BEs

Important Note:  NIST Database defines Adventitious Hydrocarbon C (1s) BE = 284.8 eV for all insulators.

Histogram indicates:  29.2 eV for Geo based on 11 literature BEs Histogram indicates:  32.9 eV for GeO2 based on 7 literature BEs

 
 

Table #6


NIST Database of Ge (3d5/2) Binding Energies

NIST Standard Reference Database 20, Version 4.1

Data compiled and evaluated
by
Alexander V. Naumkin, Anna Kraut-Vass, Stephen W. Gaarenstroom, and Cedric J. Powell
©2012 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

Important Note:  NIST Database defines Adventitious Hydrocarbon C (1s) BE = 284.8 eV for all insulators.

 

Element Spectral Line Formula Energy (eV) Reference
Ge 3d La15Ge3Fe 25.80  Click
Ge 3d La5Ge3 26.00  Click
Ge 3d La5Ge3Fe 26.00  Click
Ge 3d La15Ge9Ni 26.40  Click
Ge 3d Ge 28.60  Click
Ge 3d Ge 28.80  Click
Ge 3d Ge 29.00  Click
Ge 3d Ge 29.00  Click
Ge 3d Ge 29.00  Click
Ge 3d Ge 29.10  Click
Ge 3d Ge 29.15  Click
Ge 3d Cu88Ge12 29.20  Click
Ge 3d Ge 29.20  Click
Ge 3d Ge 29.20  Click
Ge 3d Ge/GeOx 29.25  Click
Ge 3d Ge 29.30  Click
Ge 3d Ge 29.40  Click
Ge 3d Ge 29.40  Click
Ge 3d Ge 29.40  Click
Ge 3d Si1-xGex:H 29.40  Click
Ge 3d Ge 29.45  Click
Ge 3d GeS 29.50  Click
Ge 3d Ge/GeOx 29.51  Click
Ge 3d Ge/GeOx 29.54  Click
Ge 3d Ge/GeOx 29.58  Click
Ge 3d Zn0.203Ge0.401P0.328 29.60  Click
Ge 3d Ge/GeOx 29.64  Click
Ge 3d Ge 29.65  Click
Ge 3d GeTe 29.65  Click
Ge 3d Ge 29.70  Click
Ge 3d GeAs2 29.70  Click
Ge 3d GeTe3As2 29.90  Click
Ge 3d GeTe 30.00  Click
Ge 3d GeTe2 30.10  Click
Ge 3d GeTeAs2S2 30.20  Click
Ge 3d GeAs2S3 30.35  Click
Ge 3d GeS2 30.40  Click
Ge 3d Ge/GeO2 30.40  Click
Ge 3d GeS 30.50  Click
Ge 3d Ge0.50Se0.50 30.60  Click
Ge 3d GeSe 30.70  Click
Ge 3d Ge2Se3 30.80  Click
Ge 3d GeSe 30.90  Click
Ge 3d Bi15.6Ge20.1Se64.3 30.90  Click
Ge 3d GeSe2 31.00  Click
Ge 3d Bi1.1Ge28.0Se70.9 31.00  Click
Ge 3d Bi10.3Ge23.9Se65.8 31.00  Click
Ge 3d Bi10Ge20Se70 31.00  Click
Ge 3d GeSe2 31.10  Click
Ge 3d Bi6.5Ge25.2Se68.3 31.10  Click
Ge 3d Ge28.8Se71.2 31.10  Click
Ge 3d (GeSe2)60(Tl2Se)40 31.10  Click
Ge 3d GeSe3 31.20  Click
Ge 3d [Ge(C6H5)4] 31.20  Click
Ge 3d Bi4Ge20Se76 31.20  Click
Ge 3d Ge0.43Se0.57 31.20  Click
Ge 3d GeSe2 31.30  Click
Ge 3d GeSe2 31.30  Click
Ge 3d GeSe2 31.30  Click
Ge 3d GeSe2 31.30  Click
Ge 3d GeSe2 31.30  Click
Ge 3d GeSe2 31.30  Click
Ge 3d GeSe2 31.30  Click
Ge 3d Ge0.33Se0.67 31.30  Click
Ge 3d Ge0.27Se0.73 31.30  Click
Ge 3d Ge0.23Se0.77 31.30  Click
Ge 3d Ge0.20Se0.80 31.40  Click
Ge 3d PbGeO3 31.60  Click
Ge 3d (PbF2)0.15(PbGeO3)0.85 31.70  Click
Ge 3d (PbF2)0.2(PbGeO3)0.8 31.70  Click
Ge 3d [GeI(C6H5)3] 31.80  Click
Ge 3d Ge20Se80 31.80  Click
Ge 3d [GeCl(C6H5)3] 31.80  Click
Ge 3d [GeBr(C6H5)3] 31.80  Click
Ge 3d (PbF2)0.05(PbGeO3)0.95 31.80  Click
Ge 3d (PbF2)0.1(PbGeO3)0.9 31.85  Click
Ge 3d (PbF2)0.4(PbGeO3)0.6 31.90  Click
Ge 3d (PbF2)0.3(PbGeO3)0.7 32.00  Click
Ge 3d (PbF2)0.7(PbGeO3)0.3 32.10  Click
Ge 3d (PbF2)0.5(PbGeO3)0.5 32.20  Click
Ge 3d (GeSe2)70(Tl2Se)30 32.30  Click
Ge 3d (PbF2)0.6(PbGeO3)0.4 32.30  Click
Ge 3d GeO2 32.50  Click
Ge 3d GeO2 32.50  Click
Ge 3d GeOx/Ge 32.86  Click
Ge 3d GeO2 32.90  Click
Ge 3d GeOx/Ge 32.97  Click
Ge 3d GeOx/Ge 32.99  Click
Ge 3d GeO2/Ge 33.00  Click
Ge 3d GeOx/Ge 33.04  Click
Ge 3d GeO2 33.10  Click
Ge 3d GeO2 33.10  Click
Ge 3d GeO2 33.10  Click
Ge 3d GeO2 33.10  Click
Ge 3d GeOx/Ge 33.10  Click
Ge 3d Si0.380Ge0.05O0.615 33.30  Click
Ge 3d Si0.297Ge0.115O0.588 33.50  Click
Ge 3d Si0.397Ge0.9O0.594 33.60  Click
Ge 3d (GeSe2)80(Tl2Se)20 34.20  Click
Ge 3d (GeSe2)90(Tl2Se)10 35.90  Click
Ge 3d GeSe2 36.20  Click

→  Periodic Table 

 


Statistical Analysis of Binding Energies in NIST XPS Database of BEs

 

 

→  Periodic Table 

 

Advanced XPS Information Section

Expert Knowledge, Spectra, Features, Guidance and Cautions  

for XPS Research Studies on Germanium Materials

 

 

 

Expert Knowledge Explanations

→  Periodic Table 

 

 

Germanium Chemical Compounds

 

Peak-fits and Overlays of Chemical State Spectra

Pure Germanium, Geo:  Ge (3d)
Cu (2p3/2) BE = 932.6 eV		 GeO2:  Ge (3d)
C (1s) BE = 285.0 eV		 Ge3N4:  Ge (3d)
C (1s) BE = 285.0 eV

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

Overlay of Ge (3d) Spectra shown Above

C (1s) BE = 285.0 eV

Chemical Shift between Ge and GeO2:   3.6 eV
 Chemical Shift between Ge and Ge3N4:  2.5 eV

 

→  Periodic Table 

 


Germanium Oxide (GeO2)
pressed pellet or exposed bulk of single crystal

Survey Spectrum from GeO2
Flood gun is ON, C (1s) BE = 285.0 eV
 Ge (3d) Chemical State Spectrum from GeO2
Flood gun is ON, C (1s) BE = 285.0 eV
  . 
O (1s) Chemical State Spectrum from GeO2
Flood gun is ON, C (1s) BE = 285.0 eV
 C (1s) Chemical State Spectrum from GeO2
Flood gun is ON, C (1s) BE = 285.0 eV
  . 
  Ge (2p3/2) Chemical State Spectrum from GeO2
Flood gun is ON, C (1s) BE = 285.0 eV
 
  . 
Valence Band Spectrum from GeO2
Flood gun is ON, C (1s) BE = 285.0 eV
 Auger Signals from GeO2
Flood gun is ON, C (1s) BE = 285.0 eV

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

 


Germanium Chemical Compounds

 

Germanium Silicide, GeSi

Survey Spectrum Ge (3d) Spectrum
  . 
Si (2p) Spectrum Ge (2p3/2) Spectrum
  .
Valence Band Spectrum  
 
   
   
   
   

→  Periodic Table 

 

Quantitation Details and Information

Quantitation by XPS is often incorrectly done, in many laboratories, by integrating only the main peak, ignoring the Electron Loss peak, and the satellites that appear as much as 30 eV above the main peak.  By ignoring the electron loss peak and the satellites, the accuracy of the atom% quantitation is in error.

When using theoretically calculated Scofield cross-section values, the data must be corrected for the transmission function effect, use the calculated TPP-2M IMFP values, the pass energy effect on the transmission function, and the peak area used for calculation must include the electron loss peak area, shake-up peak area, multiplet-splitting peak area, and satellites that occur within 30 eV of the main peak.

 

Quantitation from Pure, Homogeneous Binary Compound
composed of Germanium – GeO2

This section is focused on measuring and reporting the atom % quantitation that results by using:

  • Scofield cross-sections,
  • Spectra corrected to be free from Transmission Function effects
  • A Pass Energy that does not saturate the detector system in the low KE range (BE = 1000-1400 eV)
  • A focused beam of X-ray smaller than the field of view of the lens
  • An angle between the lens and the source that is ~55 deg that negates the effects of beta-asymmetry
  • TPP-2M inelastic mean free path values, and
  • Either a linear background or an iterated Shirley (Sherwood-Proctor) background to define peak areas

The results show here are examples of a method being developed that is expected to improve the “accuracy” or “reliability” of the atom % values produced by XPS.

 

→  Periodic Table 

 

 

 

Flood Gun Effect on Native Oxide of Germanium

 

Native Oxide of Germanium Sheet – Sample GROUNDED
versus
Native Oxide of Germanium Sheet – Sample FLOATING

 

 

Native Oxide of Germanium Sheet – Sample Grounded

Electron Flood Gun:  0 Voltage (FG OFF), Min Voltage versus Max Voltage

Ge (3d) O (1s) C (1s)
     
→  Periodic Table     

 

Native Oxide of Germanium Sheet – Sample Floating

Electron Flood Gun:  0 Voltage (FG OFF), Min Voltage versus Max Voltage

Ge (3d) O (1s) C (1s)
     
     

 

→  Periodic Table 

 

 

XPS Study of UHV Gas Captured by Freshly Ion Etched Germanium
 
Reveals Chemical Shifts and Chemical States that Develop from Highly Reactive Pure Geo

Surface was strongly Ar+ ion etched to remove all contaminants, and
then allowed to react overnight with the UHV Gases – CO, H2, H2O, O2 & CH4
that normally reside inside on the walls of the chamber, on the sample stage,
and on the nearby un-etched surface a total of 10-14 hours.  UHV pump was a Cryopump.
Initial spectra are at the front.  Final spectra are at the rear. Flood gun is OFF.
 
 
 
Ge (3d) Signal
  O (1s) Signal C (1s) Signal
     
 
 
Copyright ©:  The XPS Library
 

 

Auger Chemical State Spectra from Ge3N4
using Charge Control – AES (HER)

 

160 nA of current with Argon Ions and Tilt for Charge Control

33nA of current, NO Argon Ions for Charge Control

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

 

Germanium Alloys

   
XxCu XxCu
→  Periodic Table   
XxCu XxCu

 

Copyright ©:  The XPS Library 

 

 

XPS Facts, Guidance & Information

→  Periodic Table 

    Element   Germanium (Ge)
  
    Primary XPS peak used for Peak-fitting:   Ge (3d)  
    Spin-Orbit (S-O) splitting for Primary Peak:   Spin-Orbit splitting for “d” orbital, ΔBE = 0.6 eV
  
    Binding Energy (BE) of Primary XPS Signal:   29 eV
  
    Scofield Cross-Section (σ) Value:   Ge (3d) = 1.42       Ge (2p3/2) =24.15
  
    Conductivity:   Ge resistivity =  
Native Oxide suffers Differential Charing		  
    Range of Ge (3d5/2) Chemical State BEs:   29 – 32 eV range   (Geo to GeF2)  
    Signals from other elements that overlap
Ge (3d) Primary Peak:		   W (4f)  
    Bulk Plasmons:   ~xx eV above peak max for pure  
    Shake-up Peaks:   xx  
    Multiplet Splitting Peaks:   xx  

 

 

 General Information about
XXX Compounds:		   xx  
    Cautions – Chemical Poison Warning  

xx 

  

Copyright ©:  The XPS Library 

→  Periodic Table 

 

Information Useful for Peak-fitting Ge (3d5/2)

  • FWHM (eV) of Ge (3d) for Pure Geo :  ~0.64 eV using 50 eV Pass Energy after ion etching:
  • FWHM (eV) of Ge (3d) for GeO2:  ~1.28 eV using 50 eV Pass Energy  (before ion etching)
  • Binding Energy (BE) of Primary Signal used for Measuring Chemical State Spectra:  29.3 eV for Ge (3d) with +/- 0.2 uncertainty
  • List of XPS Peaks that can Overlap Peak-fit results for Ge (3d):  W (4f)

→  Periodic Table 

 

General Guidelines for Peak-fitting XPS Signals

  • Typical Energy Resolution for Pass Energy (PE) setting used to measure Chemical State Spectra on Various XPS Instruments
    • Ag (3d5/2) FWHM (eV) = ~0.95 eV for PE 50 on Thermo K-Alpha
    • Ag (3d5/2) FWHM (eV) = ~1.00 eV for PE 80 on Kratos Nova
    • Ag (3d5/2) FWHM (eV) = ~0.95 eV for PE 45 on PHI VersaProbe
  • FWHM (eV) of Pure Elements: Ranges from 0.4 to 1.0 eV across the periodic table
  • FWHM of Chemical State Peaks in any Chemical Compound:  Ranges from 1.1 to 1.6 eV  (in rare cases FWHM can be 1.8 to 2.0 eV)
  • FWHM of Pure Element versus FWHM of Oxide:  Pure element FWHM << Oxide FWHM  (e.g. 0.8 vs 1.5 eV, roughly 2x)
  • If FWHM Greater than 1.6 eV:  When a peak FWHM is larger than 1.6 eV, it is best to add another peak to the peak-fit envelop.
  • BE (eV) Difference in Chemical States: The difference in chemical state BEs is typically 1.0-1.3 eV apart.  In rare cases, <0.8 eV.
  • Number of Peaks to Use:  Use minimum. Do not use peaks with FWHM < 1.0 eV unless it is a or a conductive compound.
  • Typical Peak-Shape:  80% G: 20% L,   or Voigt : 1.4 eV Gaussian and 0.5 eV Lorentzian
  • Spin-Orbit Splitting of Two Peaks (due to Coupling):  The ratio of the two (2) peak areas must be constrained.

Notes:

  • Other Oxidation States can appear as small peaks when peak-fitting
  • Pure element signals normally have asymmetric tails that should be included in the peak-fit.
  • Gaseous state materials often display asymmetric tails due to vibrational broadening.
  • Peak-fits of C (1s) in polymers include an asymmetric tail when the energy resolution is very high.
  • Binding energy shifts of some compounds are negative due to unusual electron polarization.

→  Periodic Table 

 

Contaminants Specific to Germanium

  • Germanium develops a thick native oxide due to the reactive nature of clean Germanium .
  • The native oxide of Ge Ox is 2-8 nm thick.
  • Germanium thin films often have a low level of iron (Fe) in the bulk as a contaminant or to strengthen the thin film
  • Germanium forms a low level of carbide when the surface is ion etched inside the analysis chamber

 

Commonplace Contaminants

  • Carbon and Oxygen are common contaminants that appear on nearly all surfaces. The amount of Carbon usually depends on handling.
  • Carbon is usually the major contaminant.  The amount of carbon ranges from 5-50 atom%.
  • Carbon contamination is attributed to air-borne organic gases that become trapped by the surface, oils transferred to the surface from packaging containers, static electricity, or handling of the product in the production environment.
  • Carbon contamination is normally a mixture of different chemical states of carbon (hydrocarbon, alcohol or ether, and ester or acid).
  • Hydrocarbon is the dominant form of carbon contamination. It is normally 2-4x larger than the other chemical states of carbon.
  • Carbonate peaks, if they appear, normally appear ~4.5 eV above the hydrocarbon C (1s) peak max BE.
  • Low levels of carbonate is common on many s that readily oxidize in the air.
  • High levels of carbonate appear on reactive oxides and various hydroxides.  This is due to reaction between the oxide and CO2 in the air.
  • Hydroxide contamination peak is due to the reaction with residual water in the lab air or the vacuum.
  • The O (1s) BE of the hydroxide (water) contamination normally appears 0.5 to 1.0 eV above the oxide peak
  • Sodium (Na), Potassium (K), Sulfur (S) and Chlorine (Cl) are common trace to low level contaminants
  • To find low level contaminants it is very useful to vertically expand the 0-600 eV region of the survey spectrum by 5-10X
  • A tiny peak that has 3 or more adjacent data-points above the average noise of the background is considerate to be a real peak
  • Carbides can appear after ion etching various reactive s.  Carbides form due to the residual CO and CH4 in the vacuum.
  • Ion etching can produce low oxidation states of the material being analyzed.  These are newly formed contaminants.
  • Ion etching polymers by using standard Ar+ ion guns will destroy the polymer, converting it into a graphitic type of carbon

→  Periodic Table 

 

Data Collection Guidance

  • Chemical state differentiation can be difficult
  • Collect principal Ge (3d) peak as well as Ge (2p3).
  • Long time exposures (high dose) to X-rays can degrade various polymers, catalysts, high oxidation state compounds
  • During XPS analysis, water or solvents can be lost due to high vacuum or irradiation with X-rays or Electron flood gun
  • Auger signals can sometimes be used to discern chemical state shifts when XPS shifts are very small

→  Periodic Table 

 

Data Collection Settings for Germanium (Ge)

  • Conductivity:  Germanium readily develops a native oxide that is sensitive to Flood Gun – Differential Charging Possible – float sample recommended
  • Primary Peak (XPS Signal) used to measure Chemical State Spectra:  Ge (3d) at 29 eV
  • Recommended Pass Energy for Measuring Chemical State Spectrum:  40-50 eV    (Produces Ag (3d5/2) FWHM ~0.7 eV)
  • Recommended # of Scans for Measuring Chemical State Spectrum:  4-5 scans normally   (Use 10-25 scans to improve S/N)
  • Dwell Time:  50 msec/point
  • Step Size:  0.1 eV/point   (0.1 eV/step or 0.1 eV/channel)
  • Standard BE Range for Measuring Chemical State Spectrum:  20-40 eV
  • Recommended Extended BE Range for Measuring Chemical State Spectrum: 0-100 eV
  • Recommended BE Range for Survey Spectrum:  -10 to 1,100 eV   (above 1,100 eV there are no useful XPS signals, except for Ge and Ga)
  • Typical Time for Survey Spectrum:  3-5 minutes for newer instruments, 5-10 minutes for older instruments
  • Typical Time for a single Chemical State Spectrum with high S/N:  5-10 minutes for newer instruments, 10-15 minutes for older instruments 

→  Periodic Table 

 

Effects of Argon Ion Etching

  • Carbides appear after ion etching Ge and various reactive s.  Carbides form due to the residual CO and CH4 in the vacuum.
  • Ion etching can produce low oxidation states of the material being analyzed.  These are newly formed contaminants.
  • Ion etching polymers by using standard Ar+ ion guns will destroy the polymer, converting it into a graphitic type of carbon

 

→  Periodic Table 

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Gas Phase XPS or UPS Spectra
 
 
     
     
     
     
     
     
     
     
     
 
 
 
 

 

Chemical State Spectra from Literature
 
 
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