Auger Electron Spectroscopy (AES) is a surface-sensitive analysis approach that uses a high-energy electron beam as the excitation source. The atoms that have been stimulated by the electron beam then relax, releasing "Auger" electrons. The kinetic energy of the Auger electrons emitted is typical of the sample's top element.
For studying minor surface features, AES is a highly effective technique. Alfa Chemistry has unrivaled expertise in handling Auger analysis demands. We've been employing Auger electron spectroscopy to solve various coating analysis problems for years.
Learn About Auger Electron Spectroscopy
To ionize electrons on the surface of a solid sample, AES uses a scanning-focused high-energy electron source. The excited atom will then relax via the electron shell-to-shell transition, and the energy difference between the two shells must be released as X-rays. These Auger electrons' kinetic energy is measured and has elemental properties. Because Auger electrons have a limited escape depth, AES can only examine the top few atomic layers of sample material.
AES is highly beneficial when evaluating particles and small regions because it can investigate sizes smaller than 25 nm due to the narrow diameter of the electron beam. When the film is too thin, it's also a viable option. Sputtering allows AES to sample thin film stacks to a depth of one micron or more.
Fig 1. Scanning electronic image and AES spectrum of graphene layer on SiO2/Si substrate. (Xu M. X, et al. 2010)
Most notably, AES is a semi-quantitative method, which means we normally deliver results depending on the equipment manufacturer's recommended sensitivity parameters. If more precise results are required, look at recognized constituents and compare them to unknown materials.
It can either scan the electron beam over a variable-size area or focus it on certain surface features of interest. Auger electron spectroscopy can also do a deep examination of the composition when used in conjunction with a sputter ion gun.
Auger Electron Spectroscopy of Alfa Chemistry
Whether studying sub-micron particles to determine the source of contamination in the coating or evaluating coating flaws to examine the root cause of failure, Alfa Chemistry's vast Auger electron spectroscopy knowledge provides direct analytical advantages. Alfa Chemistry continues to apply its expertise to help customers in a variety of industries solve difficult problems.
The following are the major elements of our laboratory's AES capabilities:
- Quantitative analysis of elements other than hydrogen and helium
- The typical element detection limit is 0.1 atomic% from the top few nanometers
- Scanning Electron Microscope
- Scanning Auger Microscope (SAM) allows the collection of surface chemical maps with lateral resolution better than 1μm.
- The chemical state information of certain elements can be obtained, especially Al, Mg, Si, etc.
- Sputter depth analysis reveals chemical depth information
The following are some examples of AES applications:
- Growth or removal of oxides or surface separation materials
- Characterization of surface unevenness
- Wet Chemical Pitting Research
- Analysis of evaporated or deposited layers
- Improvement of chemical cleaning or etching process and analysis of dry stains
- Surface oxide thickness in semiconductor processing-depth analysis
- Chemical characterization and depth analysis of sputtering layer process
Reference
- Xu M. X, et al. (2020). "Auger Electron Spectroscopy: A Rational Method for Determining Thickness of Graphene Films." ACS Nano. 4(5): 2937-2945.
