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


 

Silicon (Si)

 

Man-made Silicon Carbide – SiC Man-made Boule of Silicon – Sio Quartz – SiO2

 

  Page Index
  • Expert Knowledge Explanations
    • PDMS, siloxane
    • n-Si, p-Si, and un-doped
    • SiOx, Silicate, SiO2
    • Ion etching effects


Silicon (Sio) Metalloid 
Peak-fits, BEs, FWHMs, and Peak Labels

Silicon (Sio) Metalloid (single crystal)
Si (2p) Spectrum using PE = 10 eV – raw spectrum

Ultra-high energy resolution, freshly cleaved in lab air
Silicon (Sio) Metalloid (single crystal)
Peak-fit of Si (2p) Spectrum using PE = 10 eV (w/o asymm)
using 2p3/2 to 2p1/2 spin-orbit splitting for peak-fit,  ΔBE=0.602, peak area ratio = 2.0


.
 Silicon (Sio) Metalloid (single crystal)
Si (2p) Spectrum using PE=50 eV – raw spectrum

Normal high energy resolution setting, wafer freshly cleaved in lab air
Silicon (Sio) Metalloid (single crystal)
Peak-fit of Si (2p) Spectrum (w/o asymm)

using 2p3/2 to 2p1/2 spin-orbit splitting for peak-fit,  ΔBE=0.602, peak area ratio = 2.0


.
Silicon (Sio) Metalloid (single crystal)
Si (2p) and Si (2s) Spectrum with Plasmons

raw
Silicon (Sio) Metalloid (single crystal)
Si (2p) and Si (2s) Spectrum with Plasmons
labelled


.
Silicon (Sio) Metalloid (single crystal)
Si (2s) Spectrum – raw

Silicon (Sio) Metalloid (single crystal)
Si (2s) Spectrum – peak-fit


.
Silicon (Sio) Metalloid (single crystal)
Valence Band Spectrum – not ion etched

SiO2 (amorphous silica)
Valence Band Spectrum – not ion etched


.
Silicon (Sio) Metalloid (single crystal)
Adventitious C (1s) Spectrum – not ion etched
Silicon (Sio) Metalloid (single crystal)
Freshly-Formed UHV Carbon after Ion Etching (inside cryopump system)


 

Survey Spectrum of Silicon (Sio) Metalloid
with Peaks Integrated, Assigned and Labelled

 


 

Survey Spectrum of Silicon Dioxide (SiO2)
with Peaks Integrated, Assigned and Labelled

 Periodic Table 


 

XPS Signals for Pure Silicon, (Sio) 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
Si (2s) 151 0.955 30.0
Hg (4f) overlaps Si (2p1/2) 100.0 0.276 30.9
Si (2p3/2) 99.4 0.541 30.9
Si (3s) 8 0.0808 32.5
Si (3p) 4 0.014

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

Plasmon Peaks

SiO2 Energy Loss Peaks

Intrinsic Plasmon Peak:  ~17 eV above peak max
Expected Bandgap for Si: 1.12 eV
Expected Bandgap for SiO2: 7.8 eV 

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

 


 

Comparison of
Plasmon Peaks from Pure Sio to
Energy Loss Peaks from SiO2
no ion etching – freshly cleaved – fractured

Si (2p) to Si (2s) range with plasmon peaks for Sio   (ΔBE = ~18 eV) Si (2p) to Si (2s) range with energy loss peaks for SiO(ΔBE = ~22 eV)


.
Overlay of
Si Plasmon Peaks with SiO2 Energy Loss Peaks
Vertically Expanded Overlay of
Si Plasmon Peaks with SiO2 Energy Loss Peaks

.
Si (KLL) Auger Peaks from Pure Sio
 Fresh exposed bulk produced by extensive Ar+ ion etching

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

Artefacts Caused by Argon Ion Etching

C (1s) from Carbides formed by Etching Argon Trapped in Silicon

 


 

Side-by-Side Comparison of
Sio, Si Native Oxide & Pure Silicon Dioxide
(SiO2, amorphous Silica)
Peak-fits, BEs, FWHMs, and Peak Labels

Si Native Oxide Pure SiO(amorphous, Silica)
Si (2p) from FRESH Si Native Oxide
Flood Gun OFF
As-Measured, C (1s) at 285.4 eV 
Si (2p) from SiO2 (Silica)- fresh exposed bulk
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV


.
C (1s) from FRESH Native Si Oxide
on Silicon
As-Measured, C (1s) at 285.4 eV (Flood Gun OFF)

C (1s) from SiO2 (silica)- fresh exposed bulk
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 


.
O (1s) from FRESH Native Si Oxide
on Silicon
As-Measured, C (1s) at 285.4 eV (Flood Gun OFF)

O (1s) from SiO2 (silica) – fresh exposed bulk
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 


.
Valence Band Spectrum of Native Si Oxide – fresh bulk exposed
on Silicon
As-Measured, C (1s) at 285.4 eV (Flood Gun OFF)

Valence Band Spectrum of SiO2 (amorphous silica) – fresh fracture
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 

Survey Spectrum of Silicon (Si) Native Oxide
with Peaks Integrated, Assigned and Labelled

 

 

Survey Spectrum of Pure Silicon Dioxide, SiO2
(amorphous silica)
with Peaks Integrated, Assigned and Labelled

Copyright ©:  The XPS Library 



Overlays of Si (2p) Spectra for
Sio metalloid, Native Si Oxide and Pure SiO2 Optical Lens

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

 Overlay of Sio metalloid and Native Si Oxide – Si (2p)
Study of Ion Etch Effect
Native Oxide C (1s) = 285.4 eV  (Flood gun OFF)
Chemical Shift: 1.5
 Overlay of Sio metalloid and Pure SiO2 (silica)  – Si (2p)
Pure Oxide C (1s) = 285.0 eV, not ion etched
Chemical Shift:  4.4

Copyright ©:  The XPS Library 

 

Overlay of Si (2p)
Sio metalloid, Native Si Oxide, & Pure SiO2 (silica)  

 

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 



 

Silicon Minerals, Gemstones, and Chemical Compounds

 

Natural Silicon – Sio Sodium Silicate – Na2SiO3 – Waterglass Potassium Silicate – K2SiO4 Magnesium Silicate – Mg2SiO4 – Talc

 



 

Six (6) Chemical State Tables of Si (2p) BEs

 

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

 



 

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 (2p3/2) 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
    • There are uncertainties and error ranges in nearly all BEs 
      • Flood guns
    • 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 (2p3/2) 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

Si (2p) 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
Si 14 Mg2Si 98.5 eV 285.0 eV The XPS Library
Si 14 NiSi (N*6) 98.8 eV 99.7 eV 284.8 eV Avg BE – NIST
Si 14 MoSi2 99.0 eV 285.0 eV The XPS Library
Si 14 Si3H2 (N*4) 99.0 eV 284.8 eV Avg BE – NIST
Si 14 Si (p) 99.2 eV 285.0 eV The XPS Library
Si 14 Si – element 99.5 eV 285.0 eV The XPS Library
Si 14 Si (n) 99.8 eV 285.0 eV The XPS Library
Si 14 SiC (N*5) 100.4 eV 100.7 eV 284.8 eV Avg BE – NIST
Si 14 SiC 100.5 eV 285.0 eV The XPS Library
Si 14 Si2O 100.8 eV 285.0 eV The XPS Library
Si 14 Si3N4 (N*12) 101.5 eV 102.1 eV 284.8 eV Avg BE – NIST
Si 14 Si-O 101.5 eV 285.0 eV The XPS Library
Si 14 Si3N4 101.7 eV 285.0 eV The XPS Library
Si 14 SiCN 101.8 eV 285.0 eV The XPS Library
Si 14 B4Si  (N*1) 101.9 eV 284.8 eV Avg BE – NIST
Si 14 Pyrope 102.1 eV 285.0 eV The XPS Library
Si 14 HfSiOx 102.3 eV 285.0 eV The XPS Library
Si 14 Si2O3 102.3 eV 285.0 eV The XPS Library
Si 14 Mica 102.4 eV 285.0 eV The XPS Library
Si 14 M-SiO3 (N*2) 102.4 eV 103.3 eV 284.8 eV Avg BE – NIST
Si 14 Si-PDMS 102.4 eV 102.6 eV 285.0 eV The XPS Library
Si 14 Al2SiO5 102.8 eV 285.0 eV The XPS Library
Si 14 Aluminosilicates 102.8 eV 285.0 eV The XPS Library
Si 14 SiON 102.8 eV 103.0 eV 285.0 eV The XPS Library
Si 14 LiAlSi2O6 103.0 eV 285.0 eV The XPS Library
Si 14 SiO2 103.1 eV 285.0 eV The XPS Library
Si 14 SiO2 thermal 103.2 eV 285.0 eV The XPS Library
Si 14 SiO2 fused 103.4 eV 285.0 eV The XPS Library
Si 14 Si-(OH)4  Opal 103.7 eV 285.0 eV The XPS Library

Charge Referencing

  • (N*number) identifies the number of NIST BEs that were averaged to produce the BE in the middle column.
  • Binding Energy Scale Calibration expects 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

Si (2p) Chemical State BEs from:  “PHI Handbook”

C (1s) BE = 284.8 eV

 Periodic Table 

Copyright ©:  Ulvac-PHI


Table #3

Si (2p) Chemical State BEs from:  “Thermo-Scientific” Website

C (1s) BE = 284.8 eV

Chemical state Binding energy Si (2p) / eV
Si element 99.4
Si3N4 101.7
ZrSiO4 102
Organic Si ~102
Aluminosilicate 102.7
SiO2 103.5

 Periodic Table 

Copyright ©:  Thermo Scientific 


Table #4

Si (2p) 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

Si (2p) 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
Si 2p Silicon 99.2 ±0.4 98.8 99.5
Si 2p Silicides 99.7 ±0.3 99.4 99.9
Si 2p Carbides 100.4 ±0.5 99.9 100.9
Si 2p Nitrides 101.9 ±0.4 101.5 102.2
Si 2p Silicones (Silanes) 102.4 ±0.5 101.9 102.9
Si 2p Silicates 102.5 ±0.5 102.0 103.0
Si 2p Silica 103.6 ±0.4 103.2 103.9

 Periodic Table 



 

Histograms of NIST BEs for Si (2p) BEs

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

Histogram indicates:  99.4 eV for Sio based on 37 literature BEs
Doping type is Unknown

n-Si can be 0.6 eV smaller than p-Si
Histogram indicates:  103.5 eV for SiO2 based on 54 literature BEs

Histogram indicates:  101.9 eV for Si3N4 based on 15 literature BEs Histogram indicates:  99.2 eV for SiHx based on 16 literature BEs

Histogram indicates:  102.5 eV for -((CH3)2SiO)n– based on 7 literature BEs
PDMS = Silicone Oil = Poly-dimethylsiloxane
Histogram indicates:  100.6 eV for SiC based on 11 literature BEs

Table #6


NIST Database of Si (2p) 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
Si 2p Tm/Si 98.00  Click
Si 2p Tm/Si 98.00  Click
Si 2p Gd5Si3 98.10  Click
Si 2p Si 98.40  Click
Si 2p Si/Ba 98.40  Click
Si 2p FeSi 98.60  Click
Si 2p GdSi 98.60  Click
Si 2p (-O)3Si(CH2)3NHC(O)(CH2)7C(O)OH/Si 98.60  Click
Si 2p Si 98.70  Click
Si 2p Er/Si 98.70  Click
Si 2p SiO2/Si 98.70  Click
Si 2p Tm/Si 98.70  Click
Si 2p Tm/Si 98.70  Click
Si 2p Tm/Si 98.70  Click
Si 2p TiSi2 98.80  Click
Si 2p SiO2/Si 98.80  Click
Si 2p SiO2/Si 98.80  Click
Si 2p Au34Si66 98.80  Click
Si 2p Si/(CH3(CH2)16C(O)O)2Cd 98.80  Click
Si 2p Si/AlAs 98.89  Click
Si 2p Si 98.90  Click
Si 2p Si 98.90  Click
Si 2p FeSi2 98.90  Click
Si 2p Er/Si 98.90  Click
Si 2p Er/Si 98.90  Click
Si 2p SiO2/Si 98.90  Click
Si 2p Au59Si41 98.90  Click
Si 2p Si/Y 98.90  Click
Si 2p Gd3Si5 98.90  Click
Si 2p (-O)3Si(CH2)3NHC(O)(CH2)16CH3/Si 98.90  Click
Si 2p Si/(-O)3Si(CH2)3NHC(O)(CH2)11NO2 98.90  Click
Si 2p Si:H 98.90  Click
Si 2p Si/SiO2/Zr 98.90  Click
Si 2p Zr1.02Si0.96Te1.02 98.90  Click
Si 2p Si/Pt 98.97  Click
Si 2p Si/Pt 98.97  Click
Si 2p Si 99.00  Click
Si 2p FeSi 99.00  Click
Si 2p Tm/Si 99.00  Click
Si 2p Tm/Si 99.00  Click
Si 2p Tm/Si 99.00  Click
Si 2p Si/(-O)3Si(CH2)3NHC(O)(CH2)11NH2 99.00  Click
Si 2p Si/(-O)3Si(CH2)3NHC(O)(CH2)7C(O)OCH3 99.00  Click
Si 2p Si/O2 99.00  Click
Si 2p Si/Ir 99.02  Click
Si 2p Si/Ir 99.07  Click
Si 2p Si 99.10  Click
Si 2p Si 99.10  Click
Si 2p SiO2/Si 99.10  Click
Si 2p Au45Si55 99.10  Click
Si 2p SiOx/Si 99.10  Click
Si 2p Si/SiO2/Zr 99.10  Click
Si 2p Si 99.20  Click
Si 2p Si 99.20  Click
Si 2p FeSi2 99.20  Click
Si 2p Si/Y 99.20  Click
Si 2p SiF4/Si 99.20  Click
Si 2p SiF4/Si 99.20  Click
Si 2p Si 99.22  Click
Si 2p Ag/SiHx 99.23  Click
Si 2p CoSi2/Si 99.27  Click
Si 2p Si 99.30  Click
Si 2p Si 99.30  Click
Si 2p Si 99.30  Click
Si 2p Si 99.30  Click
Si 2p FeSi2 99.30  Click
Si 2p Er/Si 99.30  Click
Si 2p Er/Si 99.30  Click
Si 2p SiOx/Si 99.30  Click
Si 2p SiOx/Si 99.30  Click
Si 2p Ta2O5/Si 99.30  Click
Si 2p Ta2O5/Si 99.30  Click
Si 2p Ta2O5/Si 99.30  Click
Si 2p Si/SiO2 99.30  Click
Si 2p SiOx/Si 99.34  Click
Si 2p Ag/SiHx 99.35  Click
Si 2p SiO2/Si 99.37  Click
Si 2p SiOx/Si 99.40  Click
Si 2p Si 99.40  Click
Si 2p Si 99.40  Click
Si 2p MoSi2.2 99.40  Click
Si 2p Y2O3/SiO2/Si 99.40  Click
Si 2p Y/SiO2/Si 99.40  Click
Si 2p (ZrO2)91(Y2O3)9/Si 99.40  Click
Si 2p (ZrO2)91(Y2O3)9/Si 99.40  Click
Si 2p Si/SiO2 99.40  Click
Si 2p Si 99.42  Click
Si 2p Si/Ba 99.45  Click
Si 2p Si/GaAs 99.49  Click
Si 2p SiOx 99.50  Click
Si 2p O2/Si 99.50  Click
Si 2p SiO2/Si 99.50  Click
Si 2p SiHx 99.50  Click
Si 2p SiHx 99.50  Click
Si 2p Si/Y 99.50  Click
Si 2p SiOx/Si 99.50  Click
Si 2p Si/GaAs 99.50  Click
Si 2p Pd/Si 99.50  Click
Si 2p Si/Ir 99.52  Click
Si 2p Si/GaAs 99.52  Click
Si 2p Si/GaAs 99.53  Click
Si 2p Si/Ba 99.55  Click
Si 2p Si/GaAs 99.55  Click
Si 2p Si/GaAs 99.55  Click
Si 2p Si/GaAs 99.57  Click
Si 2p Si 99.59  Click
Si 2p Si 99.60  Click
Si 2p Si 99.60  Click
Si 2p Si 99.60  Click
Si 2p Si 99.60  Click
Si 2p Si 99.60  Click
Si 2p Si 99.60  Click
Si 2p Si 99.60  Click
Si 2p SiH0.1 99.60  Click
Si 2p Si/GaAs 99.60  Click
Si 2p Si 99.61  Click
Si 2p Si/Ir 99.62  Click
Si 2p SiH0.2 99.65  Click
Si 2p Si 99.67  Click
Si 2p FeSi2 99.70  Click
Si 2p Pt/Si 99.72  Click
Si 2p Si 99.80  Click
Si 2p Te/Si 99.80  Click
Si 2p Te/Si 99.80  Click
Si 2p SiO1.4 99.80  Click
Si 2p SiO0.4 99.80  Click
Si 2p Si/GaAs 99.81  Click
Si 2p SiC 99.85  Click
Si 2p Si/GaAs 99.87  Click
Si 2p SiO2/Si 99.92  Click
Si 2p Si/GaAs 99.92  Click
Si 2p Si/GaAs 99.95  Click
Si 2p Si/GaAs 99.96  Click
Si 2p Si/GaAs 99.99  Click
Si 2p SiC1.5 100.00  Click
Si 2p Si/GaAs 100.08  Click
Si 2p SiC 100.10  Click
Si 2p SiC1.3 100.10  Click
Si 2p SiC 100.20  Click
Si 2p SiC 100.20  Click
Si 2p SiC1.9 100.20  Click
Si 2p SiC2.3 100.20  Click
Si 2p Pt/Si 100.22  Click
Si 2p SiC 100.30  Click
Si 2p SiC1.7 100.30  Click
Si 2p SiC 100.40  Click
Si 2p SiC 100.40  Click
Si 2p SiC 100.40  Click
Si 2p SiOx 100.40  Click
Si 2p O2/Si 100.40  Click
Si 2p Pd2Si 100.50  Click
Si 2p (-(CH3)x(SiHy)-)n 100.50  Click
Si 2p SiC 100.60  Click
Si 2p SiC 100.60  Click
Si 2p Si3N4 100.60  Click
Si 2p SiC 100.70  Click
Si 2p Pd[C&=CSi(CH3)3]2(P(C6H5)3)2 100.70  Click
Si 2p SiC 100.80  Click
Si 2p SiC 100.80  Click
Si 2p SiOx 101.10  Click
Si 2p O2/Si 101.10  Click
Si 2p (-CH2CH(Si(OCH3)3)-)n 101.10  Click
Si 2p (-CH2C((CH3)C(O)O(CH2)3Si(OCH3)3)-)n 101.10  Click
Si 2p (-OCH2CH(CH2O(CH2)3Si(OCH3)3)-)n 101.10  Click
Si 2p (-CH2CH(Si(CH3)3)-)n 101.20  Click
Si 2p CaF2/Si 101.30  Click
Si 2p CaF2/Si 101.30  Click
Si 2p CaF2/Si 101.30  Click
Si 2p (SiO2)0.517(Na2O)0.299(Fe2O3)0.18 101.30  Click
Si 2p (-Si(OCH3)2O-)xAly 101.40  Click
Si 2p Si3N4 101.50  Click
Si 2p (PbF2)9.0(PbO)63.7(SiO2)27.3 101.50  Click
Si 2p (PbF2)17.2PbO)54.3(SiO2)28.5 101.50  Click
Si 2p (SiO2)0.563(Na2O)0.304(Fe2O3)0.13 101.50  Click
Si 2p (PbF2)12.7(PbO)58.2(SiO2)29.1 101.60  Click
Si 2p (PbF2)3.2(PbO)68.7(SiO2)28.1 101.60  Click
Si 2p AlN7OSi5 101.60  Click
Si 2p Na12[Al12Si12O48].18H2O 101.60  Click
Si 2p (SiO2)0.618(Na2O)0.298(Fe2O3)0.085 101.60  Click
Si 2p (-Si(CH3)2O-)n 101.62  Click
Si 2p (Si(CH3)2-O-)n 101.62  Click
Si 2p (-Si(CH3)2-C6H4-Si(CH3)2-O-)n 101.70  Click
Si 2p Si2N2O 101.70  Click
Si 2p Al2N6O2Si4 101.70  Click
Si 2p Al3N5O3Si3 101.70  Click
Si 2p Al4N4O4Si2 101.70  Click
Si 2p (MgO)0.047Si3N4 101.70  Click
Si 2p Al0.55Si0.10P0.35O2.2 101.80  Click
Si 2p Si3N4/Si 101.80  Click
Si 2p Si3N4 101.80  Click
Si 2p (PbF2)15.6(PbO)56.0(SiO2)28.4 101.80  Click
Si 2p Na11.9(AlO2)11.9(SiO2)12.1 101.80  Click
Si 2p (SiO2)0.667(Na2O)0.287(Fe2O3)0.046 101.80  Click
Si 2p Si3N4/InP 101.90  Click
Si 2p SiOx 101.90  Click
Si 2p O2/Si 101.90  Click
Si 2p Si3N4/Si 101.90  Click
Si 2p Na7.5Al6Si6O24S4.5 101.90  Click
Si 2p SiO0.93 101.90  Click
Si 2p B22.5Si18.2O18.5N40.5 101.90  Click
Si 2p SiN1.1 101.90  Click
Si 2p Si3N4/Si 102.00  Click
Si 2p SiO 102.00  Click
Si 2p SiO2(Al2O3)0.22 102.00  Click
Si 2p C6H9O(CH2)2Si((CH3)2)OSi((CH3)2)(CH2)2C6H9O 102.00  Click
Si 2p B22.4Si16.7O24.1N36.5 102.00  Click
Si 2p Si3N4 102.04  Click
Si 2p (-Si(CH3)2O-)n 102.10  Click
Si 2p (Si(CH3)2-O-)n 102.10  Click
Si 2p (-Si(CH3)(C6H5)O-)n 102.10  Click
Si 2p (Si(CH3)(C6H5)-O-)n 102.10  Click
Si 2p Si3N4 102.10  Click
Si 2p SiO0.35N1.1/Si 102.10  Click
Si 2p SiO2(Al2O3)0.22 102.10  Click
Si 2p K0.7(NaCa)0.3(Mg2.84Fe0.02)Al1.2Si2.8O10(OH1.5F0.50) 102.10  Click
Si 2p K0.7(NaCa)0.3(Mg2.84Fe0.02)Al1.2Si2.8O10(OH1.5F0.50) 102.10  Click
Si 2p B17.8Si17.0O47.5N19.1 102.10  Click
Si 2p (-Si(CH3)2O-)n 102.20  Click
Si 2p (-Si(C6H5)(CH3)O-)n 102.20  Click
Si 2p (-Si(C6H5)2O-)n 102.20  Click
Si 2p (MoO3)90(SiO)10 102.20  Click
Si 2p SiO0.7N0.9/Si 102.20  Click
Si 2p SiO2(Al2O3)0.55 102.20  Click
Si 2p SiO2(Al2O3)0.55 102.20  Click
Si 2p SiO1.02 102.20  Click
Si 2p SiO1.05 102.20  Click
Si 2p (SiO2)0.694(Na2O)0.306 102.20  Click
Si 2p Na85.4(AlO2)85.4(SiO2)106.6 102.20  Click
Si 2p (-Si(CH3)2O-)n 102.30  Click
Si 2p (-Si(CH3)2O-)n 102.30  Click
Si 2p Al0.44Si0.41P0.13O2.1 102.30  Click
Si 2p (MoO3)80(SiO)20 102.30  Click
Si 2p CaTiSiO5 102.30  Click
Si 2p K0.9(Mg1.56Fe1.14Ti0.11)Al0.96Si3.0O10(OH1.44F0.56) 102.30  Click
Si 2p K0.9(Mg1.56Fe1.14Ti0.11)Al0.96Si3.0O10(OH1.44F0.56) 102.30  Click
Si 2p Na88Al86Si106O384 102.30  Click
Si 2p C6H9O(CH2)2Si((CH3)2)OSi((CH3)2)OSi((CH3)2)OSi((CH3)2)(CH2)2C6H9O 102.30  Click
Si 2p Ca6(Si6O17)(OH)2 102.30  Click
Si 2p Na69(NH4)13Al82Si110O384 102.30  Click
Si 2p Ca10(PO4)4.4(SiO4)1.24(CO3)0.36(OH)1.12 102.30  Click
Si 2p (-Si(CH3)2O-)n 102.40  Click
Si 2p (-Si(CH3)2O-)n 102.40  Click
Si 2p (-Si(CH3)2O-)n 102.40  Click
Si 2p (-CH2CH(Si(OCH3)3)-)n 102.40  Click
Si 2p (-CH2C((CH3)C(O)O(CH2)3Si(OCH3)3)-)n 102.40  Click
Si 2p (-OCH2CH(CH2O(CH2)3Si(OCH3)3)-)n 102.40  Click
Si 2p SiO2(Al2O3)0.22 102.40  Click
Si 2p Y2O3/SiO2/Si 102.40  Click
Si 2p Si35O26N38 102.40  Click
Si 2p Si33O44N22 102.40  Click
Si 2p SiO1.19 102.40  Click
Si 2p SiO1.24 102.40  Click
Si 2p NaAlSi2O6.H2O 102.40  Click
Si 2p HSCH2(CH2)9CH(OH)+C18H37SiCl3 102.40  Click
Si 2p (Na,Ca)0.5Fe1.0[Mg1.2Fe1.5Al2.3][Si6.8Al1.2O22](OH)2 102.40  Click
Si 2p (SiO2)55(CaO)21.5(Al2O3)14.5(B2O3)6.0(Na2O)0.8(MgO)0.6(Fe2O3)0.4(TiO2)0.3(F2)0.6(FO2)0.3(K2O)0.1 102.40  Click
Si 2p HOOC-(Si(CH3)2-O-)n-COOH 102.40  Click
Si 2p Na52(NH4)30Al82Si110O384 102.40  Click
Si 2p Na15(NH4)66Al82Si110O384 102.40  Click
Si 2p (-Si(CH3)2O-)n 102.50  Click
Si 2p (Si(CH3)2-O-)n 102.50  Click
Si 2p (MoO3)70(SiO)30 102.50  Click
Si 2p SiF4/Si 102.50  Click
Si 2p SiF4/Si 102.50  Click
Si 2p SiO2(Al2O3)2.1 102.50  Click
Si 2p (MoO3)70(SiO)30 102.60  Click
Si 2p O2/Sr/Si 102.60  Click
Si 2p (-Si(OCH3)2O-)n 102.60  Click
Si 2p Al2Si2O5(OH)4 102.65  Click
Si 2p (MoO3)70(SiO)30 102.70  Click
Si 2p (MoO3)60(SiO)40 102.70  Click
Si 2p (-O)3Si(CH2)3NHC(O)(CH2)11NO2/Si 102.70  Click
Si 2p (-O)3Si(CH2)3NHC(O)(CH2)7C(O)OCH3/Si 102.70  Click
Si 2p (-O)3Si(CH2)3NHC(O)(CH2)7C(O)OH/Si 102.70  Click
Si 2p SiO2(Al2O3)0.55 102.70  Click
Si 2p Al6Si2O13 102.70  Click
Si 2p SiO1.35 102.70  Click
Si 2p Al2SiO5 102.70  Click
Si 2p (MoO3)70(SiO)30 102.80  Click
Si 2p SiO2/Si 102.80  Click
Si 2p (MoO3)50(SiO)50 102.80  Click
Si 2p ZrSiO4 102.80  Click
Si 2p Si32O49N19 102.80  Click
Si 2p SiO1.52 102.80  Click
Si 2p SiO1.49 102.80  Click
Si 2p Na54.5(AlO2)54.5(SiO2)137.5 102.80  Click
Si 2p H3Na45(AlO2)56(SiO2)136 102.80  Click
Si 2p (K,Ca)2[Mg4.3Fe0.7][Si7.2Al0.8O22](OH)2 102.80  Click
Si 2p (Ca1.6Mg0.4)[Mg2.0Fe1.9Al1.0][Si7.2Al0.8O22](OH,Cl) 102.80  Click
Si 2p CH3Si((C6H5)2)OSi(CH3)(C6H5)OSi((C6H5)2)CH3 102.82  Click
Si 2p Al0.35Si0.48P0.16O2.2 102.90  Click
Si 2p (-O)3Si(CH2)3NHC(O)(CH2)11NH2/Si 102.90  Click
Si 2p (-O)3Si(CH2)3NHC(O)(CH2)16CH3/Si 102.90  Click
Si 2p ZrO0.15H2.25Na0.08[(AlO2)2.63(SiO2)93.37] 102.90  Click
Si 2p Na60Al63Si128O384 102.90  Click
Si 2p Ca2[Mg5][Si8O22]OH2 102.90  Click
Si 2p Na26.5H24.5Al51Si141O384 102.90  Click
Si 2p Ca2[Mg5][Si8O22](OH)2 102.90  Click
Si 2p SiO2 103.00  Click
Si 2p SiO2 103.00  Click
Si 2p SiO2/Si 103.00  Click
Si 2p NiSiO3 103.00  Click
Si 2p SiO2(Al2O3)2.1 103.00  Click
Si 2p Ta2O5/Si 103.00  Click
Si 2p Ta2O5/Si 103.00  Click
Si 2p Si/(CH3(CH2)16C(O)O)2Cd 103.00  Click
Si 2p Pt4H7Na41(AlO2)56(SiO2)136 103.00  Click
Si 2p H20Na28(AlO2)56(SiO2)136 103.00  Click
Si 2p Al0.041Si0.264Na0.04K0.02O0.635 103.00  Click
Si 2p H7Na41(AlO2)56(SiO2)136 103.00  Click
Si 2p Pt4H20Na28(AlO2)56(SiO2)136 103.00  Click
Si 2p H11Na37(AlO2)56(SiO2)136 103.00  Click
Si 2p Pt4H3Na45(AlO2)56(SiO2)136 103.00  Click
Si 2p Pt4H11Na37(AlO2)56(SiO2)136 103.00  Click
Si 2p SiO2/Si 103.10  Click
Si 2p SiO2/Si 103.10  Click
Si 2p SiO2 103.10  Click
Si 2p Ta2O5/Si 103.10  Click
Si 2p SiO1.78 103.10  Click
Si 2p SiO2 103.20  Click
Si 2p SiO2 103.20  Click
Si 2p SiO2 103.20  Click
Si 2p SiO2 103.20  Click
Si 2p SiOx 103.20  Click
Si 2p O2/Si 103.20  Click
Si 2p Al0.2Si0.8O2.2 103.20  Click
Si 2p O2/Sr/Si 103.20  Click
Si 2p O2/Sr/Si 103.20  Click
Si 2p O2/Sr/Si 103.20  Click
Si 2p SiO2/Si 103.20  Click
Si 2p SiO2/Si 103.20  Click
Si 2p SiO2 103.20  Click
Si 2p CH3(CH2)17SiCl3/Al 103.20  Click
Si 2p Na5.2(NH4)46.8Al52Si140O384 103.20  Click
Si 2p SiO1.91 103.20  Click
Si 2p B22.5Si18.2O18.5N40.5 103.20  Click
Si 2p Si0.284Zr0.031O0.657F0.028 103.20  Click
Si 2p B17.8Si17.0O47.5N19.1 103.20  Click
Si 2p B22.4Si16.7O24.1N36.5 103.20  Click
Si 2p SiO2/Si 103.22  Click
Si 2p SiOx/Si 103.30  Click
Si 2p SiO2 103.30  Click
Si 2p SiO2/Si 103.30  Click
Si 2p SiO2 103.30  Click
Si 2p SiO2 103.30  Click
Si 2p Na0.6H27.4Al28Si164O384 103.30  Click
Si 2p Si0.251Zr0.074O0.651F0.025 103.30  Click
Si 2p B15.2Si17.9O64.0N3.0 103.30  Click
Si 2p B19.7Si15.2O57.2N7.8 103.30  Click
Si 2p Si0.255Zr0.072O0.665F0.008 103.30  Click
Si 2p SiO2 103.40  Click
Si 2p SiO2 103.40  Click
Si 2p (-OCH2CH(CH2O(CH2)3Si(OCH3)3)-)n 103.40  Click
Si 2p SiO2 103.40  Click
Si 2p SiO2 103.40  Click
Si 2p SiO2/Si 103.40  Click
Si 2p SiO2/Si 103.40  Click
Si 2p SiO2/Si 103.40  Click
Si 2p SiO1.9 103.40  Click
Si 2p SiO2 103.40  Click
Si 2p SiO2 103.40  Click
Si 2p SiO2 103.40  Click
Si 2p SiO2 103.40  Click
Si 2p O2/Si0.8Ge0.2/Si 103.40  Click
Si 2p Si/O2 103.40  Click
Si 2p SiO2/Al/Mo 103.40  Click
Si 2p SiO2/Si 103.41  Click
Si 2p SiO2/Si 103.49  Click
Si 2p SiO2 103.50  Click
Si 2p SiO2 103.50  Click
Si 2p (-CH2CH(Si(OCH3)3)-)n 103.50  Click
Si 2p (-CH2C((CH3)C(O)O(CH2)3Si(OCH3)3)-)n 103.50  Click
Si 2p SiO2/Si 103.50  Click
Si 2p SiO2 103.50  Click
Si 2p SiO2 103.50  Click
Si 2p SiO2 103.50  Click
Si 2p SiO2 103.50  Click
Si 2p B15.9Si19.0O65.1 103.50  Click
Si 2p Si0.397Ge0.9O0.594 103.50  Click
Si 2p Si0.284Zr0.042O0.656F0.017 103.50  Click
Si 2p Si0.255Zr0.061O0.675F0.008 103.50  Click
Si 2p Si0.294Zr0.029O0.670F0.006 103.50  Click
Si 2p Si0.057Zr0.269O0.597F0.078 103.50  Click
Si 2p Si0.277Zr0.043O0.642F0.038 103.50  Click
Si 2p Si0.314Zr0.012O0.655F0.019 103.50  Click
Si 2p SiOx/Si 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p SiO2/Si 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p SiO2 103.60  Click
Si 2p B19.2Si15.3O65.4 103.60  Click
Si 2p Pt/SiO2/Si 103.61  Click
Si 2p Mg2[Mg5][Si8O22]OH2 103.65  Click
Si 2p Mg2[Mg5][Si8O22](OH)2 103.65  Click
Si 2p SiO2/Si 103.67  Click
Si 2p SiO2 103.70  Click
Si 2p SiO2 103.70  Click
Si 2p SiO2 103.70  Click
Si 2p SiO2 103.70  Click
Si 2p SiO2/Si 103.70  Click
Si 2p SiO2/Si 103.70  Click
Si 2p SiO2 103.70  Click
Si 2p SiO2 103.70  Click
Si 2p SiO2 103.70  Click
Si 2p SiO2 103.70  Click
Si 2p SiO2.05 103.70  Click
Si 2p SiO2.08 103.70  Click
Si 2p Na0.2H7.4Al7.6Si184.4O384 103.70  Click
Si 2p Si0.316Zr0.013O0.664F0.008 103.70  Click
Si 2p Si0.300Zr0.028O0.640F0.032 103.70  Click
Si 2p Si0.322Zr0.005O0.655F0.019 103.70  Click
Si 2p SiO2 103.80  Click
Si 2p SiO2 103.80  Click
Si 2p (-Si(CH3)2O-)n 103.80  Click
Si 2p SiO2 103.80  Click
Si 2p SiO2 103.80  Click
Si 2p SiO2 103.80  Click
Si 2p SiO2 103.80  Click
Si 2p SiO1.8 103.80  Click
Si 2p SiO1.4 103.80  Click
Si 2p SiO0.4 103.80  Click
Si 2p Si0.380Ge0.05O0.615 103.80  Click
Si 2p SiO2 103.90  Click
Si 2p SiO2/Mo 103.90  Click
Si 2p SiO2/Al/Mo 103.90  Click
Si 2p Si0.334O0.649F0.017 103.90  Click
Si 2p Si0.334O0.661F0.005 103.90  Click
Si 2p Si0.328Zr0.001O0.665F0.007 103.90  Click
Si 2p SiOx 104.00  Click
Si 2p O2/Si 104.00  Click
Si 2p SiO2 104.00  Click
Si 2p SiO2 104.00  Click
Si 2p SiO2 104.00  Click
Si 2p SiO2 104.00  Click
Si 2p SiO2 104.00  Click
Si 2p SiO2 104.10  Click
Si 2p Si0.297Ge0.115O0.588 104.50  Click
Si 2p SiF4/Si 105.00  Click
Si 2p SiF4/Si 105.00  Click
Si 2p SiF4/Si 107.70  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 Silicon Materials

 


 

Expert Knowledge Examples & Explanations

 


 

Silicon Chemical Compounds

 

Peak-fits and Overlays of Chemical State Spectra

Pure Silicon:  Si (2p)
Cu (2p3/2) BE = 932.6 eV
Silicone Oil (PDMS):  Si (2p)
C (1s) BE = 285.0 eV
SiO2:  Si (2p)
C (1s) BE = 285.0 eV

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

Overlay of Si (2p) Spectra shown Above

C (1s) BE = 285.0 eV

 

 Periodic Table 


 

FRESH Silicon (Si) Native Oxide on Silicon
Naturally Formed at 25 Co 1 atm after freshly cleaving in lab air (age ~30 min)

Survey Spectrum from FRESH Native Oxide on Sio
Flood gun is OFF, C (1s) BE = 285.4 eV
Si (2p) Chemical State Spectrum from FRESH Native Oxide on Sio
Flood gun is OFF, C (1s) BE = 285.4 eV


 
O (1s) Chemical State Spectrum from FRESH Native Oxide on Sio
Flood gun is OFF, C (1s) BE = 285.4 eV
C (1s) Chemical State Spectrum from FRESH Native Oxide on Sio
Flood gun is OFF, C (1s) BE = 285.4 eV

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 

 


 

Silicon Dioxide (SiO2), silica – fresh fractured bulk
Silica (amorphous) optical lens – fractured to expose bulk

Survey Spectrum from SiO2 Silica optical lens
Flood gun is ON, C (1s) BE = 285.0 eV
Freshly cleaved to expose bulk
Si (2p) Chemical State Spectrum SiO2 Silica optical lens
Flood gun is ON, C (1s) BE = 285.0 eV
Freshly cleaved to expose bulk


   .
O (1s) Chemical State Spectrum from SiO2 Silica optical lens
Flood gun is ON, C (1s) BE = 285.0 eV
Freshly cleaved to expose bulk
C (1s) Chemical State Spectrum from SiO2 Silica optical lens
Flood gun is ON, C (1s) BE = 285.0 eV
Freshly cleaved to expose bulk


.
Si (2p) Chemical State Spectrum from SiO2 Silica optical lens
Flood gun is ON, C (1s) BE = 285.0 eV
Freshly cleaved to expose bulk
Si (2s) Chemical State Spectrum from SiO2 Silica optical lens
Flood gun is ON, C (1s) BE = 285.0 eV
Freshly cleaved to expose bulk


.
Valence Band Spectrum from SiO2 Silica optical lens
Flood gun is ON, C (1s) BE = 285.0 eV
Freshly cleaved to expose bulk
Si (2p) and Si (2s) spectrum from SiO2 Silica optical lens
Flood gun is ON, C (1s) BE = 285.0 eV
Freshly cleaved to expose bulk

 

Comparison of Si (2s) and Si (2p) Peak-shapes
from SiO2 (silica)

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 

 


 

Silicon Chemical Compounds

Surveys and Peak-fits

 

PDMS (silicone oil)    -(CH3)2Si-O)n
Survey Spectrum
Si (2p) O (1s) C (1s) at 285.0 eV
 Periodic Table 

 

Water Glass Solution – Na2Si3O7
Survey Spectrum

Si (2p) O (1s) C (1s)
 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.

 Periodic Table 

 


 

 

Flood Gun Effect on Native Oxide of Silicon

 

Native Oxide of Silicon Ribbon – Sample GROUNDED
versus
Native Oxide of Silicon Ribbon – Sample FLOATING

 


 

Native Oxide of Silicon Disk – Sample Grounded

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

Si (2p) O (1s) C (1s)
Differential Shift of SiOx Peak is due to
Differential Charging
Differential Shift of O (1s) Peak is due to
Differential Charging
Differential Shift of Adventitious Carbon
is a Slightly Larger
Features Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

Native Oxide of Silicon Disk – Sample Floating

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

Si (2p) O (1s) C (1s)
All Peaks Shift Linearly
NO Differential Charging
All Peaks Shift Linearly
NO Differential Charging
All Peaks Shift Linearly
NO Differential Charging
Features Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

XPS Study of UHV Gas Capture by Freshly Ion Etched Silicon 
Reveals Chemical Shifts and Chemical States that Develop from Highly Reactive Pure Sio

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.
Si (2p) Signal
 O (1s) Signal C (1s) Signal
Copyright ©:  The XPS Library


 

AES Study of UHV Gas Capture by Freshly Ion Etched Silicon 

Silicon ribbon was ion etched and allowed to react with residual UHV gases overnight – ~14 hr run.

Si (LMM) Signal:
Si at front -> SiOx at rear (normal display)
O (KLL) Signal:
Si at rear -> SiOx at rear



  .
Si (KLL) Signal:
Si at front -> SiOx at rear (normal display)
C (KLL) Signal:
Si at front -> SiOx at rear (normal display)

 

AES Chemical State Spectra from Sio exposed bulk
using High Energy Resolution (HSA)

 
Si (KLL) Signal:
Low Energy Resolution Mode (4%)
Si (KLL) Signal:
High Energy Resolution Mode (0.5%)




   
Si (LMM) Signal:
Low Energy Resolution Mode (4%)
Si (LMM) Signal:
High Energy Resolution Mode (0.5%)

Features Observed

  • xx
  • xx
  • xx

 Periodic Table


 

 

Silicon Alloys

   
XxCu XxCu
 Periodic Table   
XxCu XxCu

 

Copyright ©:  The XPS Library 

 



 

XPS Facts, Guidance & Information

 Periodic Table 

    Element Silicon (Si)
 
    Primary XPS peak used for Peak-fitting : Si (2p)  
    Spin-Orbit (S-O) splitting for Primary Peak: Spin-Orbit splitting for “p” orbital, ΔBE = 0.602 eV
 
    Binding Energy (BE) of Primary XPS Signal: 100.0 eV
 
    Scofield Cross-Section (σ) Value: Si (2p) = 0.817
 
    Conductivity: Si resistivity =
SiO resistivity =
Semiconductor
 
    Range of Si (2p) Chemical State BEs: 99 – 105 eV range   (Sio to SiF2)  
Signals from other elements that overlap
Si (2p) Primary Peak:
  Hg (4f)
Bulk Plasmons:   ~17 eV above peak max for pure
Shake-up Peaks: ??
Multiplet Splitting Peaks:   not possible

 

 

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

xx 

Copyright ©:  The XPS Library 



 

Information Useful for Peak-fitting Si (2p)

  • FWHM (eV) of Si (2p3/2) from Pure Sio ~0.36 eV for Si (2p3/2) peak using 10 eV Pass Energy with no ion etching
  • FWHM (eV) of Si (2p3/2) from SiO2 xtal:  ~1.32 eV for Si (2p3/2) using 50 eV Pass Energy  (exposed bulk – cleaved in air)
  • Binding Energy (BE) of Primary Signal used for Measuring Chemical State Spectra:  99.5 eV for Si (2p3/2) with +/- 0.1 uncertainty
  • List of XPS Peaks that can Overlap Peak-fit results for Si (2p):  Hg (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 Silicon

  • Silicon develops a thin native oxide due to the reactive nature of clean Silicon .
  • The native oxide of SiOx is 2-3 nm thick.
  • Silicon thin films often have a low level of iron (Fe) in the bulk as a contaminant or to strengthen the thin film
  • Silicon 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 Si (2p) peak as well as Si (2s).
  • 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 Silicon (Si)

  • Conductivity:  Silicon 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:  Si (2p) at 10 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:  90-110 eV
  • Recommended Extended BE Range for Measuring Chemical State Spectrum:  90- 160 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 Si 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 

Copyright ©:  The XPS Library 


Gas Phase XPS or UPS Spectra


 

Chemical State Spectra from Literature
from Thermo Scientific Website

Example of Polymer contaminated by PDMS (Silicone Oil)



End of File