Auger Electron Spectroscopy (AES) is a surface-specific analytical technique that measures the elemental composition of surface layers by analyzing the emitted low-energy electrons resulting from the Auger effect. Developed in the 1960s, AES involves three steps: atomic ionization, electron emission, and analysis of the emitted electrons, and is capable of providing detailed chemical information, including depth profiling and surface imaging. The technique has significant applications in material science, including the study of thin films, corrosion resistance, and semiconductor devices.

1. Normaizatul Hanissa binti Hamdan
Amirah binti Basir

2.  Auger Electron Spectroscopy(AES) was developed in the late 1960’s.
 Its name was derived from the Auger effect that is first observed by Pierre Auger,
a French physicist in the late 1920’s.
 It is a surface specific technique utilizing the emission of low energy electrons in
the Auger process and is one of the most commonly employed surface analytical
techniques for determining the composition of the surface layers of a sample.

3.  The Auger Effect is named after its discoverer, Pierre Auger, who observed a
tertiary effect while studying photoemission processes in the 1920s. Auger
electrons are emitted at discrete energies that allow the atom of origin to be
identified.
 The idea of using electron-stimulated Auger signals for surface analysis was first
suggested in 1953 by J. J. Lander.
 The technique became practical for surface analysis after Larry Harris in 1967
demonstrated the use of differentiation to enhance the Auger signals.
 Today Auger electron spectroscopy is a powerful surface analytical tool to probe
surfaces, thin films, and interfaces.
 This utility arises from the combination of surface specificity (0.5 to 10 nm), good
spatial surface resolution (as good as 10 nm), periodic table coverage (except
hydrogen and helium), and reasonable sensitivity (100 ppm for most elements).

4.  Auger spectroscopy can be considered as involving three basic steps:
1. Atomic ionization (by removal of a core electron)
2. Electron emission (the Auger process)
3. Analysis of the emitted Auger electrons
 The last stage is simply a technical problem of detecting charged particles with
high sensitivity, with the additional requirement that the kinetic energies of the
emitted electrons must be determined.

5. Three symbol in transition label are three energy level
involved in transition
Transition label
K, L1, L2

6. 1. Ionization
 Initiated by creation of a core hole-typically
exposing the sample to a high energy fine focus
electron beam (typically having primary energy in
the range 2-10 keV)
 In diagram shown, ionization occur by removal of a
K-shell electron, and this will lead to creating holes
in the inner shell of electron.
 The vacancy must be refilled by an electron from a
higher energy level.

7. 2. Relaxation and Auger Emission
 The ionized atom that remains after the removal of
the core hole electron is in a highly excited and will
relax to lower ground state through X-ray
fluorescence and Auger emission (which we will only
discuss)
 When higher energy electron fills the hole, the energy
released is transferred to neighbour electron in outer
orbit electron.
 That electron has sufficient energy to overcome the
binding energy and work function to be ejected with
characteristics kinetic energy.

8. 3. Analysis of emitted Auger electrons
 The output of AES is referred to as an Auger spectrum. This spectrum would show
peaks at Auger electron energy levels corresponding to the atoms from which the
auger electrons were released.
 The energies of Auger transitions are specific to each element and its chemical
environment, so that its Auger spectrum acts as an elemental “fingerprint”, which
can be compared to a catalogue of known spectra.
 Each element typically has one or more “characteristic peaks” which can be used
to detect its presence in complex spectra, e.g. when organic molecules are
deposited on a surface, or when testing a surface for possible contamination.

9. • Figure shown in the Auger spectrum
of a Mo sample contaminated by O
and C. The primary beam was 3 keV
and the characteristics peak of Mo
and main contamination are shown.
• Due to the high linear background
signal, the Auger spectrum is
usually represented as a
differentiated spectrum, i.e.
𝑑𝑁
𝑑𝐸
vs. E.
• Due to the fact that the differential
of a peak (i.e. its slope) will be
represented as first a negative and
then positive double peak, it is usual
to refer only to the negative peak’s
position.

10. Figure 1: Direct spectrum Figure 2: Differentiated spectrum
that enhances AES features and
remove background signal

11.  The Auger electron has an energy given by
𝐸𝐴𝑢𝑔𝑒𝑟 = 𝐸𝑘 − 𝐸𝐿1 − 𝐸𝐿2,3 − ∅
Where Ek, EL1, and EL2,3 are the binding energies of K1, L1 and L2,3 of electron
orbits of the atom. Ø is the work function.

12. 

14. Electron source
and opticalcolumn
•To focus the
electron beam
from an electron
source onto the
specimen surface
by a suitable
optical column.
Ion optical column
•Cleaning the
sample surface.
•Sputtering for
depth profiling.
Electron energy
analyzer
•Measure the
number of ejected
electrons(N) as a
function of
electron energy
(E).
•Should have high
transmission
efficiency,
compact size and
ease of use of
cylindrical mirror
analyzer.
Secondary electron
detector and a
pulse counter
•Electrons exiting
the analyzer and
arrived at the
detector are
amplified and
counted by an
electron
multiplier.
•Pulse counting
measure the
electron intensity
Computer control
and data display
systems
•Setting up
conditions for
analysis
•Acquiring and
storing data
efficiently
•Processing data
•Display results in
form of spectra

15. 1) JAMP-9510F Auger Microprobe by JOEL USA Inc.
2) XPS/HAXPES Scanning Microprobe by Physical Electronics, Inc in USA.
3) PHOIBOS ARPES Analyzer by SPECSGROUP in Berlin, Germany.
4) In situ Real Time AugerProbe by STAIBS INSTRUMENTS GmbH (EUROPE AND ASIA)
OR STAIB INSTRUMENTS, Inc (North and South America).

16. Qualitative analysis
Quantitative analysis
Chemical information
Auger Depth Profiling
Auger Images and Linescans
Research and Industry

17.  Obtained a survey spectrum with relatively modest resolution in a fairly short
time.
 Most elements have significant Auger transition in the range of energy between 0
eV to 1000 eV.
 Auger electron with energies greater than 1000 eV are less-surface sensitive
because these electrons have longer inelastic mean free paths.

18.  Determine the chemical composition of solid surfaces by calculating the Auger
peak intensity measurement.
 Peak intensitites are characterized by the peak-to –peak heights.
 Method of Auger quantification:
1. first principles Auger intensity calculation
2. standards of known composition
3. elemental relative intensity factor

19.  Changes in chemical state can be deduced from changes in Auger peak positions,
intensities, and shapes.
 However, the process is challenging because Auger process involves three energy
levels.
 More detailed electronic structure information such as hybridization, electron
delocalization, screening effects may be obtained from quantitative spectral
lineshape analysis.

20.  One of four modes of Auger operation (point analysis, line scan and surface
imaging is the other three modes)
 Process of obtaining the chemical composition as a function of depth below the
surface.
 By changing the geometry of the experiment as the depth analysis depends on the
emission angle of the Auger electron.
 Category of this method:
1. Non-destructive,
2. Sputtering by noble gas ions
3. Mechanical sectioning.

21.  Scanning Auger microscope contains a secondary electron detector (SED) for
performing secondary electron microscopy (SEM) imaging that provide surface
topographic information.
 The imaging provides surface topographic by taking account the background
information and enhance chemical information when performing scanning Auger
electron spectroscopy.

22.  AES depth profiling used for monitoring chemical composition. (detecting small
defects – less than 500Amstrongthat play critical role in small semiconductor
devices.
 It is used to study ceramic thin film materials. To characterize thin films that has
potential applications in electro-optic devices, pyroelectric and micro
electromechanical devices.
 Useful for studying microscopic inclusion (chemical inhomogenities) present in
protective thin film that inhibit the corrosion of stainless steel.