Auger Electron Spectroscopy (AES, Auger)

Auger Electron Spectroscopy (AES or Auger) is a surface-sensitive analytical technique that utilizes a high-energy electron beam as an excitation source. Atoms that are excited by the electron beam can subsequently relax, leading to the emission of “Auger” electrons. The kinetic energies of the emitted Auger electrons are characteristic of elements present within the top 3-10nm of the sample.

Auger Electron Spectroscopy SMART chart

AES is part of our Smart Chart Series. In addition, due to the range of spot sizes, it provides excellent surface sensitivity and small spot size.

This technique was named after French physicist Pierre Victor Auger in 1923. However, most people now recognize Austrian-Swedish physicist Lise Meitner as the person that first that discovered that the emission of electrons from surfaces of atoms with can create energy signatures.

Key Applications

With a small electron beam diameter, AES is very useful when investing particles and small area as it has the ability to investigate sizes smaller than 25 nm. It also provides a good alternative when thin films are too thin for EDS​ analysis. AES can sample thin film stacks to a depth to a micron or more​ with sputtering.

Above all, AES is a Semi-quantitative method meaning that we typically provide results based on standard sensitivity factors provided by the equipment manufacturer. There more accurate results are required, these can be obtained by looking at known compositions, and comparing them to the unknown material.

The electron beam can be scanned over a variably sized area, or it can be directly focused on a specific surface feature of interest. This ability to focus the electron beam to diameters of 10-20nm makes Auger Electron Spectroscopy an extremely useful tool for elemental analysis of small surface features. Other techniques that may also be considered are XPS, and TXRF. When used in combination with a sputtering ion gun, Auger Electron Spectroscopy can also perform compositional depth profiling.

Ideal uses of Auger Electron Spectroscopy

  • Defect analysis
  • Particle analysis
  • Surface analysis
  • Small-area depth profiling
  • Thin film analysis composition
  • Metallurgical analysis

Stengths

  • Firstly, small area analysis (~20nm minimum)
  • Secondly, excellent surface sensitivity (3-10nm information depth)
  • Thirdly, good depth resolution

Limitations

  • Standards required for best quantification
  • Insulators can be difficult
  • Samples must be vacuum compatible
  • Detection sensitivity typically ≥1at%

Auger Electron Spectroscopy Technical Specifications

  • Signal Detected: Auger electrons from near surface atoms
  • Elements Detected: Li-U
  • Detection Limits: 0.1-1at%; sub-monolayer
  • Depth Resolution: 20-200Ǻ (in depth profiling mode)
  • Imaging/Mapping: Yes
  • Lateral Resolution/Probe Size: >=70Ǻ (field emission)

EAG has unmatched experience handling both routine and non-routine Auger analysis requests and for many years, has used Auger Electron Spectroscopy to address a wide variety of industrial analytical applications.

EAG’s extensive Auger Electron Spectroscopy expertise has direct analytical benefits, whether we analyze sub-μm particles to determine contamination sources in wafer processing equipment or analyze defects in electronic devices to investigate the root cause of failures. Finally, Auger analysis has extensive applications in metallurgical studies, including in the determination of oxide layer thickness of electro-polished medical devices, and EAG continually draws on its experience to help solve demanding problems from customers from many industry sectors.

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