Auger electron spectroscopy (AES) is one of several techniques for surface analysis in which the sample is probed in order to determine its elemental composition. Most of these techniques involve directing a focused beam toward a spot on the sample’s surface in order to probe it, and use detectors to analyze any emitted response.

In the case of AES, the probe is a beam of electrons. When high-energy electrons interact with atoms in the surface layer, one possible effect is that electrons from these atoms are knocked loose. The kinetic energies of these so-called Auger electrons provide information about the element from which the electrons came, as they are determined by the quantized electron energies of the atom. Thus, an electron-energy analyzer can collect the full energy spectrum and identify the elemental composition.

One benefit of the technique is that the electron beam cannot penetrate very far, making AES very sensitive to the outermost surface layers. This provides utility for applications where these layers are of particular importance, such as in the analysis of thin films on some other substrate.

Construed narrowly, this explanation makes AES a point-analysis technique, with the instrument providing analysis only of the area directly under the electron beam, which may have a diameter of only a few nanometers. However, AES is also used in a scanning mode, a technique called scanning Auger microscopy. Most commercial Auger systems are this type, with the electron beam used to scan over an area of the surface, building up a two-dimensional elemental map of the sample. For some applications, the instrument is also fitted with a sputtering system to remove the surface layer by layer, so that the instrument can perform depth profiling analyses. With the addition of other detectors for backscattered electrons, the instrument can also be operated in a mode similar to a standard scanning electron microscope (SEM). These SEM images can aid in positioning the spectrometer to analyze surface features. This capability is almost always found on commercial systems.

Other modular components can also be added, so that AES may be only one of several analysis modes in a complete surface analysis system. Other component possibilities include X-ray photoelectron spectroscopy, secondary ion MS and other forms of electron spectroscopy.

AES applications are generally confined to materials science applications, as the electron beam can be damaging to more delicate life science samples. Common applications include the study of surface chemistry, catalysts and geological samples.

Most of the significant competitors in the AES market are known primarily for surface analysis instrumentation. Thermo Fisher Scientific also competes in the marketplace. Kratos Analytical (Shimadzu) appears to have exited the market. Niche suppliers include RBD Instruments. The 2012 market demand for AES systems was about $75 million.

Auger Electron Spectroscopy at a Glance:

Leading Suppliers

• Ulvac-PHI

• JEOL

• Oxford Instruments

Largest Markets

• Academia

• Semiconductor and Electronics

• Chemicals

Instrument Cost

• $200,000–$1.25 million