Auger Electron Spectroscopy

Auger electron spectroscopy is an analytical technique that provides the atomic composition of near-surface layers in various materials science applications. The technique is based on the Auger effect, which occurs when a high-energy electron or X-ray removes an inner electron from an atom in the sample. When another electron makes a quantum transition to fill the vacancy, energy is released. Often this energy is emitted in the form of X-rays, which can be analyzed by an X-ray analyzer. However, when the Auger effect occurs, the energy is given to another electron in the form of kinetic energy, ejecting the electron from the atom without the release of any electromagnetic radiation. Because of the fixed electron energy levels in each atom, these Auger electrons have well-defined energies that provide information on the elemental composition of the sample.

The Auger effect was discovered independently in the 1920s by Lise Meitner and Pierre Auger. In a modern Auger analyzer or microscope, the Auger electrons are created by applying an electron gun to the sample, much in the manner of a scanning electron microscope (SEM). Indeed, most Auger systems also provide SEM imaging capabilities. Whereas ordinary secondary or backscattered electrons can be used to provide an image of the surface, the energy peaks that indicate the Auger electrons provide the elemental composition. Since the electrons are emitted from the surface layers in the immediate vicinity of the spot from the electron gun, Auger spectroscopy provides excellent spatial resolution of the surface, typically on the order of 10 nm. The Auger effect is also very much a surface effect, probing down only a few atomic layers into the sample. By combining Auger spectroscopy with a sputtering system to burn off layers, Auger can be used for depth profiling of samples.

Because of the modular nature of most surface analysis instruments, many other analyzers can also be added to an Auger system. Conversely, Auger analyzers can be added to existing surface analysis systems at a greatly reduced cost, compared to an entirely separate system. A complete standalone Auger system costs several hundred thousand dollars, depending on the configuration and performance.

The 2008 market demand for Auger spectroscopy systems was under $50 million, representing a decline from 2007 due primarily to weakness in semiconductor demand. Ulvac-PHI is the market-share leader. The company is a leader in surface analysis, and the PHI 700 is one of its hallmark instruments. Thermo Fisher Scientific offers multitechnique systems, such as the ESCALAB and MICROLAB, that include Auger. The third important vendor is JEOL, which has a high-resolution field emission source Auger system that can achieve an Auger spatial resolution of 8 nm, similar to the PHI 700. Other vendors include Kratos Analytical (Shimadzu) and Omicron NanoTechnology.

Auger Electron Spectroscopy at a Glance:

Leading Suppliers

• Ulvac-PHI

• Thermo Fisher Scientific


Largest Markets

• Academia

• Microelectronics

• Thin Films

Instrument Cost

• $300,000–$1 Million

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