And Auger Electron Spectroscopy (AES)

6/9/2008

Advanced Materials Characterization Workshop

X‐ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES)

Rick Haasch, Ph.D.

What is Surface Analysis?

>1000 nm 100 nm <10 nm

Bulk Analysis Thin- Thin-filmfilm Analysis Surface Analysis

The Study of the Outer-Most Layers of Materials (~10 nm).

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Particle Surface Interactions

Primary beam Secondary beam (source) (spectrometers, detectors) Ions Ions Elect rons Elect rons Photons Photons

Spatial resolution versus Detection Limit

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Particle Surface Interactions

Photoelectron Spectroscopy

Ions Ions Electrons Electrons Photons Photons

Joe E. Greene2)

X-ray Photoelectron Spectroscopy (XPS) X-ray Photoelectron Spectroscopy (XPS), also known as Electron Spectroscopy for Chemical Analysis (ESCA) is a widely used technique to investigate the chemical composition of surfaces. X-ray1 Photoelectron spectroscopy, based on the photoelectric effect,2,3 was developed in the mid-1960’s as a practical technique by Kai Siegbahn and his research group at the University of Uppsala, Sweden.4

Wilhelm Conrad Röntgen Heinrich Rudolf Hertz Albert Einstein Kai M. Siegbahn

1. W. Röntgen, 1901 Nobel Prize in Physics “in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him.” 2. H. Hertz, Ann. Physik 31,983 (1887). 3. A. Einstein, Ann. Physik 17,132 (1905). 1921 Nobel Prize in Physics “for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect.” 4. 4. K. Siegbahn, Et. Al.,Nova Acta Regiae Soc.Sci., Ser. IV, Vol. 20 (1967). 1981 Nobel Prize in Physics “for his contribution to the development of high resolution electron spectroscopy.” 6 © 2008 University of Illinois Board of Trustees. All rights reserved.

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X-ray Photoelectron Spectroscopy Small Area Detection

Electrons are extracted only from a narrow solid angle. X-ray Beam

X-ray penetration depth ~1μm. Electrons can be excited in this 10 nm entire volume. 10 μm- 1 mm dia.

X-ray excitation area ~1 mm-1 cm diameter. Electrons are emitted from this entire area

Photoelectron and Auger Electron Emission

KE (measured) = hν (known) - BE - Φspec (calibrated) Emitted Auger Electron Eincident X-ray = hν Free Electron Level

Φ Conduction Band Conduction Band Fermi Level Valence Band Valence Band

BE 2p L2,L3 2s L1

1s K

Calculate: BE = hν - KE - Φspec

BE – binding energy depends on Z, i.e. characteristic for the element

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Photoelectron and Auger Electron Emission

KE (measured) = hν (known) - BE - Φspec (calibrated) Emited X-ray Photon Eincident X-ray = hν Free Electron Level

Φ Conduction Band Conduction Band Fermi Level Valence Band Valence Band

BE 2p L2,L3 2s L1

1s K

Calculate: BE = hν - KE - Φspec

BE – binding energy depends on Z, i.e. characteristic for the element

Photoelectron and Auger Electron Emission

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Photoelectron and Auger Electron Emission

Energy Scales

Conduction Band 0 Fermi Level Valence Band Binding Energy Kinetic Energy

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Photoelectron and Auger Electron Emission

X-ray Photoelectron Spectroscopy

Conduction Band Fermi Level Valence Band

Al Kα = 1486.6 eV MKMg Kα = 1253. 6 e V

XPS can probe all of the orbitals in only the light elements. e.g. BE C 1s = 285 eV, Mg 1s =1304 eV, Au 1s ≈ 81000 eV

Predominantly, soft X-rays are used.

Photoelectron and Auger Electron Emission

Ultraviolet Photoelectron Spectroscopy

Conduction Band Fermi Level Valence Band

He II = 40.8 eV He I = 22.4 eV

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Surface Sensitivity: Electron Spectroscopy

Inelastic Mean-Free Path: The mean distance an electron can travel between inelastic scattering events.

Inelastic mean-free paths (calculated) based on TPP-2* 5

4.5

m) 4 XPS

3.5 Carbon 3 Aluminum 2.5 Copper Silver 2 Gold 1.5

elastic Mean-Free Path(n Mean-Free elastic 1 n I 0.5

0 0 500 1000 1500 2000 2500 3000 Kinetic Energy (eV) Electrons travel only a few nanometers through solids.

Surface Sensitivity: Electron Spectroscopy

Inelastic Mean-Free Path: The mean distance an electron can travel between inelastic scattering events.

Inelastic mean-free paths (calculated) based on TPP-2* 5

4.5

m) 4 Auger

3.5 Carbon 3 Aluminum 2.5 Copper Silver 2 Gold 1.5

elastic Mean-Free Path(n Mean-Free elastic 1 n I 0.5

0 0 500 1000 1500 2000 2500 3000 Kinetic Energy (eV) Electrons travel only a few nanometers through solids.

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Surface Sensitivity: Electron Spectroscopy

Assuming Inelastic Scattering Only

Beer-Lambert relationship: 0.8 I = I0exp(-d/λcosθ)

where d = depth 0.6 λ = Inelastic mean free path I/I0 0.4 at 3λ, I/I0 = 0.05

0.2 at 1000 eV, λ≈1.6 nm

0 01234 d/λ

95% of the signal comes from within 5 nm of the surface or less!

Surface Sensitivity: Electron Spectroscopy

Surface Analysis Advantage Disadvantage

Extremely surface sensitive! Extremely surface sensitive!

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Ion Sputtering

0.5 – 5 keV Ar+

•Ions striking a surface interact with a number of atoms in a series collisions. • recoiled target atoms in turn collide with atom at rest generating a collision cascade. • The initial ion energy and momentum are distributed to among the target recoil atoms. • When Ei > 1 keV, the cascade is “linear”, i.e. approximated by a series of binary collisions in a stationary matrix.

Causes physical and chemical damage

P. Sigmund, “Sputtering by ion bombardment: theoretical concepts,” in Sputtering by particle bombardment I, edited by R. Behrish, Springer-Verlag, 1981 19 © 2008 University of Illinois Board of Trustees. All rights reserved.

X-ray Photoelectron Spectrometer

Hemispherical Energy Analyzer

X-ray Monochromator

Extraction Detector Lenses

Sample 54.7 X-ray Source

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X-ray Photoelectron Spectrometer

Physical Electronics PHI 5400

Elemental Shifts

Pure Element

Fermi Level

ElectronElectron--electronelectron Binding repulsion Energy Look for changes Electron here by observing electron binding ElectronElectron--nucleusnucleus energies attraction Electron- Nucleus Separation

Nucleus

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Elemental Shifts

Core Level Binding Energies

1400

1s 2s 2p 1200

1000 3s

800 3p

600 3d Binding Energy (eV) Binding Energy 400

200 4s 4p 0 0 5 10 15 20 25 30 35 40 45 50 Atomic Number

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Elemental Shifts First-Row Transition Metals

Binding Energy (eV)

Element 2p3/2 3p Δ Sc 399 29 370 Ti 454 33 421 V 512 37 475 Cr 574 43 531 Mn 639 48 591 Fe 707 53 654 Co 778 60 718 Ni 853 67 786 Cu 933 75 858 Zn 1022 89 933

Elemental Shifts: An Example First-Row Transition Metal Nitr ides: ScN, TiN, VN, and CrN

Sc2p Metal and N Auger Lines Sc2s N1s Sc3p ScN Sc3s Ti2p Ti2s N1s Ti3p TiN Ti3s

V2p V2s N1s V3p VN V3s

ounts (arb. units) Cr2p C Cr2s N1s Cr3p CrN Cr3s

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Chemical Shifts

Electronegativity Effects

Carbon-Oxygen Bond Oxygen Atom

Electron-oxygen atom attraction Valence Level (Oxygen Electro- C 1s C 2p negativity) Binding Core Level Energy Shift to higher C 1s binding energy Electron-nucleus attraction (Loss of Electronic Screening) Carbon Nucleus 27 © 2008 University of Illinois Board of Trustees. All rights reserved.

Chemical Shifts

Functional C 1s Binding Group Energy (eV) hydrocarbon C-H, C-C 285.0 amine C-N 286.0 alcohol, ether C-O-H, C-O-C 286.5 Cl bound to C C-Cl 286.5 F bound to C C-F 287.8 carbonyl C=O 288.0

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Chemical Shifts: An Example

XPS of polymethylmethacrylate O 1s

O 1s C 1s 2 1

538 536 534 532 530 528 Binding Energy (eV)

C 1s

1000 800 600 400 200 0 Binding Energy (eV) 1 2 4 3

Chemical Shifts: An Example

XPS of polymethylmethacrylate

But,… C 1s Here is what we actually see.

1. 2.

3. 4. 4 3 2

292 290 288 286 284 282 Binding Energy (eV)

Sensitivity to chemical structures with XPS is short-ranged. Additional information or the use of complimentary methods is essential!

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Chemical Shifts: An Example

N 1s spectra of First-Row Transition Metal Nitrides: ScN, TiN, VN, and CrN

p-d hybridization 8 MO’s N 1s Anti-bonding Binding e-/Formula Energy, Unit (nominal) eV ScN -0.17 (0) 396.1 ScN

TiN 1 (1) 397.3 TiN Counts (arb. units) (arb. Counts VN 1.9 (()2) 397.0 VN CrN 2.9 (3) 396.7 CrN 399 398 397 396 395 394 Binding energy (eV)

Ultraviolet Photoelectron Spectroscopy: An Example

First-Row Transition Metal Nitrides: ScN, TiN, VN, and CrN Partially hybridized N 2p M 3d anti-bonding As the number of electrons per unit cell and M 3d bonding states states increases, from ScN to CrN, the metal 3d bands begin to fill pushing the Fermi level above the minimum in the density-of-states (DOS). The Fermi edge then becomes more dominant and the N 2p bands move to higher ScN binding energy.

TiN

ounts (arb. units) (arb.ounts VN C

CrN

1086420-2 Binding energy (eV)

J.-E. Sundgren, B.O. Johansson, A. Rockett, S.A. Barnett, J.E. Greene, American Institute of Physics Conference Surface Science Spectra, 7, 167-280, 2000. Proceedings, 149(1), 95-115 (1986). 32 © 2008 University of Illinois Board of Trustees. All rights reserved.

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Quantitative Surface Analysis: XPS

Assuming a Homogeneous sample:

Ai = detector count rate detector A = ( electrons/volume )( volume ) λcos(θ) i count rate A i Ai = ( Niσi(γ)JT(Ei) )( aλi(Εi)cosθ) Sample Dependent Terms where: N = atoms/cm3 θ σ(γ) = photoelectric (scattering) cross-section, cm2 λ λ(E ) = inelastic electron mean-free path, cm γ i Instrument Dependent Terms J=XJ = X-ray flux, photon/cm2-sec ni, nj T(E ) = analyzer transmission function J i beam a = analysis area, cm2 θ = photoelectron emission angle

Quantitative surface analysis: XPS

By assuming the concentration to be a relative ratio of atoms, we can neglect the terms that depend only on the instrument:

Ni = Ai/σiT(Ei)λi(Ei)

It is difficult to accurately determine λi so it is usually neglected. Modern acquisition and analysis software can account for the transmission function.

Ni = Ai / Si

Ci = Ai/Si / Σ Ai,j/Si,j

The values of S are determined theoretically or empirically with standards.

XPS is considered to be a semi-quantitative technique.

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Quantitative surface analysis: XPS

XPS Relative Elemental Sensitivities

12 3d

8 4f

2p 6

Relative Sensitivity Relative 4 4d 1s

0 Li B N F Na Al P Cl K Sc V M Co Cu G As Br Rb Y Nb TcRh Ag In Sb I Cs La Pr P Eu TbHo T Lu Ta Re Ir Au Tl Bi Be C O Ne M Si S Ar Ca Ti Cr Fe Ni Zn G Se Kr Sr Zr M Ru Pd Cd SnTe XeBa Ce Nd S G Dy Er Yb Hf W Os Pt Hg Pb Elemental Symbol

Quantitative surface analysis: An Example

First-Row Transition Metal Nitrides: ScN, TiN, VN, and CrN

XPS Analysis ScN TiN VN CrN

Metal 2p3/2 Major peak 400.4 455.1 513.2 574.4 Binding energy Satellitea 457.9 515.5 575.5

(eV) Metal 2p1/2 Major peak 404.9 461.0 520.7 584.0 Satellitea 463.8 523.0 585.1 N 1s 396.1 397.3 397.0 396.7 Composition As Deposited 1.13 1.00 1.02 0.73b (N/metal) After ion bombardment 0.99 0.73 0.46 0.55b Bulk value from RBS 1.11±0.03 1.02±0.02 1.06±0.02 1.04±0.02 a. The satellite is due to a transition into a relaxed final state b. The composition determination of the CrN layers by peak fitting is less reliable because the commonly used Shirley method for background subtraction does not accurately describe the experimental data.

Nitrogen/Metal peak ratio decreases after sputtering

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Angle-resolved XPS

More Surface Less Surface Sensitive Sensitive θ = 0° θ = 75° A film on B IA/IB

θ I /I θ AB alloy A B

Angle-resolved XPS: An Example Si with native oxide O 1s Si 2p Si0 Si 2s θ = 0º Si 2p

C 1s Si oxide

O 1s Si 2p Si0 θ =75= 75º Si oxide

C 1sSi 2s Si 2p

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Angle-resolved XPS: An Example

SiO2 Layer thickness calculation: Two-Layer Model- thin overlayer

Assuming only inelastic scattering and photoelectrons from layer a will not undergo an inelastic scattering event

Beer-Lambert relationship:

I = I0exp(-d/λcosθ)

Ia ∫ d a d/λ = ln(ca/cb +1)cosθ b Ib

0.3 nm Carbon Step 1: Step 2: 1.2 nm SiO2 a=Carbon, b=SiO2+Si a=Carbon+SiO2, b=Si with λ=3 nm, d=0.3 nm with λ=3 nm, d=1.5 nm Si

Imaging X-ray Photoelectron Spectrometer

Kratos AXIS Ultra Imaging Mode: Spherical mirror analyzer With the entrance aperture open, a spatially dispersed image (real image) is projected onto the detection plane.

Spectroscopy Mode: Hemispherical energy analyzer With the entrance aperture closed, an energy dispersed image (reciprocal image I.e. spectrum) is projected onto the detection plane.

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XPS Imaging: An Example

Pt catalyzed etching of patterned porous silicon O 1s

1 Si wafer Si 2s Si 2p µCP OTS Anneal C 1s OTS Pt 4f

2 Si wafer

Spin-coat Pt complex Heat Pt OTS Pt 4f

Cross-correlated, low-magnification 3 Si wafer XPS image after step 3 for the Pt 4f7/2 (shown in orange) and C 1s (shown in blue) core levels measured at 74 and Etch 285 eV, respectively. The image PSi confirms the selective deposition of the Pt-complex in the OTS-free areas of the substrate. 4 Si wafer

XPS Imaging: An Example

Pt catalyzed etching of patterned porous silicon O 1s

Si 2s 1 Si wafer C 1s Si 2p

µCP OTS Anneal

OTS Pt 4f

2 Si wafer

Spin-coat Pt complex Heat Pt OTS Pt 4f

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Ion Sputtering and Depth Profiling: An Example

Analysis of Materials for Solar Cells by XPS Depth Profiling

The amorphous-SiC/SnO2 Interface

The profile indicates a reduction of the SnO2 PhotoPhoto--voltaicvoltaic Collector occurred at the interface during deposition. ShSuch a red dtiuction would ldfftth effect the collector’s efficiency. SnO2 Sn

Solar Energy

Conductive Oxide-Oxide-SnOSnO2 Depth pp--typetype a-a-SiCSiC 500 496 492 488 484 480 aa--SiSi Binding Energy, eV

Ion Sputtering and Depth Profiling: An Example

TiN 2p3/2

2p1/2

as-deposited ounts (arb. units) (arb. ounts C Ar+ sputtered

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Ion Sputtering and Depth Profiling: An Example

ScN He I UPS s (arb. units) s (arb. t as-ditddeposited Coun Ar+ sputtered

10-1 Binding energy (eV)

ounts (arb. units) C

XPS and UPS- A Summary

XPS UPS Elements: Li and above. Elemental Analysis: Not usually, Sensitivity: 0.1 – 1 atomic % sometimes from low BE core levels. Destructive: No, some beam damage to Destructive: No,,g some beam damage to sensitive materials. sensitive materials. Elemental Analysis: Yes, semi- Chemical State Information: Yes, but quantitative without standards, complicated from valence levels, for quantitative with standards, not a trace core levels same as XPS. analysis technique. Depth Resolution: 0.5 – 5 nm. Chemical State Information: Yes, for Lateral Resolution: Several mm. most elements. Sample Types: Solid UHV-compatible, Depth Resolution: 0.5 – 5 nm. conducting or semiconducting are LlRliLateral Resolution: Spectroscopy- 1 mm best. to 40 mm, Imaging- 5 mm. Sample Types: Solid UHV-compatible, conducting, semiconducting and insulating.

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Auger Electron Spectroscopy

Auger Electron Spectroscopy (AES), is a widely used technique to investigate the composition of surfaces.

First discovered in 1923 by Lise Meitner and later independently discovered once again in 1925 by Pierre Auger1.

Lise Meitner Pierre Victor Auger

1. P. Auger, J. Phys. Radium, 6, 205 (1925).

Particle-Surface Interactions

Auger Electron Spectroscopy

Ions Ions Electrons Electrons Photons Photons

Joe E. Greene2)

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Auger Electron Spectroscopy

Incident Electron Secondary Electron Emitted Auger Electron

Free Electron Level

Conduction Band Conduction Band Fermi Level Valence Band Valence Band

2p L2,L3

2s L1

1s K

KLL Auger electron

EAuger = E(K)- E(L2,3) - E(L2,3)

EX-ray = E(K) – E(L2,3)

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Auger Electron Spectroscopy

Incident Electron Secondary Electron Emitted X-ray Photon

Free Electron Level

Conduction Band Conduction Band Fermi Level Valence Band Valence Band

2p L2,L3

2s L1

1s K

KLL Auger electron

EAuger = E(K)- E(L2,3) - E(L2,3)

EX-ray = E(K) – E(L2,3)

Relative Probability of Relaxation of a K Shell Core Hole

1.0

Auger Electron 0.8 Emission

0.6

0.4 Probability 0.2 X-ray Photon Emission 0 5 10 15 20 25 30 35 40 Atomic Number BNePCaMnZnBrZr Elemental Symbol

The light elements have a higher cross section for Auger electron emission.

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Scanning Auger Electron Spectrometer

Elemental Shifts

First-Row Transition Metals

Binding Energy (eV)

Element 2p3/2 3p Δ Sc 399 29 370 Ti 454 33 421 V 512 37 475 Cr 574 43 531 Mn 639 48 591 Fe 707 53 654 Co 778 60 718 Ni 853 67 786 Cu 933 75 858 Zn 1022 89 933

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Elemental Shifts

L. E. Davis, N. C. MacDonald, Paul W. Palmberg, G. E. Riach, R. E. Weber, Handbook of Auger Electron Spectroscopy, 2nd Edition, Physical Electronics Division, Perkin-Elmer Corp., Eden Prairie, MN 1976. 55 © 2008 University of Illinois Board of Trustees. All rights reserved.

Elemental Shifts: An Example

First-Row Transition Metal Nitrides: ScN, TiN, VN, and CrN

N(E) dN(E) 4,5 2,3 2,3 2,3

3 keV spectra - as deposited 4,5 M M 4 L 3 keV spectra - as deposited M M 2,3 2,3 M 2,3 4 2,3 4 4,5 M M 3 4,5 M M 3 M 3 M 4 3 4,5 M 2,3 2,3 M L 1 M 4,5 N KL Sc L 2,3 2,3 M Sc L 3 Sc L Sc L M 3 Sc M Sc

O M Sc N KL Sc L Sc L 4 Ti Ti M Ti 4 Ti Ti M 4 Ti 2,3 Ti M 4 Ti M 1 V V Sc M V V V V V V Sc M Sc Cr Cr Cr Ti Ti Counts (arb. units) V Counts (arb. units) Cr Cr Cr 2,3 V Cr L Cr 2,3 Cr Cr C N KL

0 200 400 600 0 200 400 600 Kinetic energy (eV) Kinetic energy (eV)

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Quantitative surface analysis: AES

Assuming a Homogeneous sample:

Ai = detector count rate detector A = ( electrons/volume )( volume ) λcos(θ) i count rate A i Ai = ( Niσi(γ)χi(1+r)JT(Ei) )( aλi(Ei)cosθ) Sample Dependent Terms where: N = atoms/cm3 θ σ(γ) = ionization (scattering) cross-section, cm2 λ χi = Auger transition probability γ r = secondary ionization coefficient

λ(Ei) = inelastic electron mean-free path, cm n n i, j Instrument Dependent Terms Jbeam J = Electron flux, electron/cm2-sec

T(Ei) = analyzer transmission function a = analysis area, cm2 θ = Auger electron emission angle

Quantitative surface analysis: AES

By assuming the concentration to be a relative ratio of atoms, we can neglect the terms that depend only on the instrument:

Ni = Ai/σiχi(1+r)T(Ei)λi(Ei)

It is difficult to accurately determine λi and r, so they are usually neglected. Modern acquisition and analysis software can account for the transmission function.

Ni = Ai / Si

Ci =A= Ai/Si / Σ Ai,j/Si,j

The values of S are determined theoretically or empirically with standards.

AES is considered to be a semi-quantitative technique.

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Quantitative surface analysis: AES

3 kV Primary Beam

10 KLL LMM MNN

0.1 Sensitivity Factor

0.01 0 20406080100 Atomic Number

Quantitative surface analysis: AES

10 kV Primary Beam

10 KLL LMM MNN r

0.1 Sensitivity Facto

0.01 0 20406080100 Atomic Number

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Quantitative surface analysis: AES

Quantitative surface analysis: An Example

First-Row Transition Metal Nitrides: ScN, TiN, VN, and CrN

AES Analysis ScN TiN VN CrN

Metal L3M2,3M2,3 (α) 337.0 384.2 435.4 486.8

Peak energy Metal L3M2,3M4,5 (β) 367.2 417.4 472.0 527.8 a b N KL2,3L2,3 (γ) 382.2 … 382.4 381.6

b Iγ/Iα 1.00 … 1.95 1.69 As-deposited b Iγ/Iβ 2.00 2.52 1.43 1.30 b Intensity After ion Iγ/Iα 1.01 … 1.54 1.14

bombardment Iγ/Iβ 1.82 2.10 1.01 0.94 Bulk composition from RBS 1.06±0.03 1.02±0.02 1.04±0.02 1.02±0.02

a. The N KL2,3L2,3 peak overlaps with the weak Sc L3M4,5M4,5 peak (see spectra). The latter peak is ~6% of the Sc L3M2,3M2,3 in the pure metal spectrum. b. For the TiN AES spectrum, the N KL2,3L2,3 and the Ti L3M2,3M2,3 exhibit severe overlap (see spectra). Therefore, the peak position of N KL2,3L2,3 is omitted in the table and the listed peak intensity ratio corresponds to the sum of N KL2,3L2,3 and Ti L3M2,3M2,3 divided by Ti L3M2,3M4,5 (i.e., Iα+γ/Iβ).

Nitrogen/Metal peak ratio decreases after sputtering

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AES Depth Profiling: An Example

(cross section)

AES Depth Profiling: An Example

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AES Imaging and Mapping: An Example

Contamination on patterned semiconductor

Survey data was used to identify Indium (In) contamination after the etching step on a patterned semiconductor . Then mapping of the In signal showed the position of contamination on the sample.

100.0μm Low magnification SEM image of general sample area

10.0 μm SEM image of a single Au pad

AES Imaging and Spectroscopy: An Example

600 400 200 0 -200

dN(E)/E C -400 Cr -600 -800 -1000 Ni 0 200 400 600 800 1000 1200 Kinetic Energy, eV

400

200

0 /E ) -200 dN(E -400 C

-600 10 μm Cr -800 0 200 400 600 800 1000 1200 Kinetic Energy, eV

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AES Imaging and Mapping: An Example

Cr Map

C Map

AES Imaging and Mapping: An Example

Ni Map

C Map

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AES Imaging and Depth Profiling: An Example

Electron Beam in combination with an SED detector allows for imaging of the sample to select the area for analysis.

x 104 COFER73.SPE 1

0.8

0.6

0.4

0.2 Fracture surface of Carbon fibers in BN matrix - analysis area outlined in black 0 c/s Ar B -0.2 N

-040.4 K A -PE

-0.6 O

Si K-T A

-0.8 PE C O

-1 50 100 150 200 250 300 350 400 450 500 550 Kinetic Energy (eV)

SPUTTER TIME (MIN.) Survey on Fiber surface at 1 min. in profile Depth profile on fiber to determine point of fracture. Variations in fracture surface interface for different sample treatments will be reflected in depth profile.

AES: A Summary

AES Elements: Li and above. Sensitivity: 0.1 – 1 atomic % Destructive: No, some beam damage to sensitive materials. Elemental Analysis: Yes, semi-quantitative without standards, quantitative with standards, not a trace analysis technique. Chemical State Information: Yes, for some elements, sometimes requires high- resolution analyzer. Depth Resolution: 0.5 – 5 nm. Lateral Resolution: 500 nm. Sample Types: Solid UHV-compatible, conducting, semiconducting.

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Surface Analysis

Acknowledgements