Auger Electron Spectroscopy (AES) makes use of an effect discovered independently by Lise Meitner and Pierre Auger in the early 1920s. When a high-energy electron interacts with an atom, a bound electron may be ejected. If another electron undergoes a quantum transition to fill the empty orbital, energy is released. Although usually this circumstance is accompanied by the emission of a photon, in the Auger effect the energy is transmitted to another electron, which is ejected from the atom.
Just as the photons have characteristic energies corresponding to energy transitions of the particular element, so too do these Auger electrons come with specific energies that can be used to identify the atom. As an instrumental technique, AES involves directing a focused beam of electrons toward a spot on the surface of the sample in order to probe it, and using electron energy detectors to analyze the emitted Auger electrons.
The signal derives from a spot as small as a few nanometers in diameter across, and the instrument can calculate the atomic composition of the surface at that location. The Auger effect is very sensitive to the surface layers of the sample, penetrating the sample to a depth of only a nanometer or so. Consequently, there is great value of the technique in analyzing thin layers and surface chemistry.
Most Auger instruments are designed to scan the analysis spot across a surface, such that a complete map of the elemental composition of the surface can be constructed. Using AES in this way is known as Scanning Auger Microscopy (SAM).
As is common in surface analysis, SAM can also be combined with other complementary techniques in a composite system, which may offer electron microscopy, photoelectron spectroscopy, electron microprobe analysis, or systems for sputtering or etching the sample to reveal the interior for analysis. In particular, electron microscopy functionality is quite common, as it aids in locating features of interest on the sample and directing the Auger probe.
The primary use of Auger spectroscopy is in materials science, rather than life science. As with many surface analysis techniques, the sample is subjected to vacuum, and Auger analysis faces particular challenges with non-conductive samples, as charge can build up, distorting the analysis. The largest specific market is in academic laboratories, where the technique is applied to the analysis of advanced materials, surface chemistry and geological samples. The largest industrial source of demand comes from the semiconductors and electronics industry, where Auger can be used to analyze surface layers for doping and thin film deposition as well as for nanostructures.
There are not very many competitors in the Auger market, which is restricted primarily to a small pool of specialist companies in surface analysis. Foremost among them is Ulvac-PHI and its famed Physical Electronics division. JEOL, a leader in electron microscopy, also has a significant business in surface analysis. The third largest vendor is Scienta Omicron, formed in May 2015 as a joint venture between Oxford Instruments (which had acquired Omicron Nanotechnology) and GDI, the Swedish parent of Scienta Scientific (see IBO 5/31/15). The joint venture together collects expertise in a number of surface analysis techniques, including Auger.
Although formerly a competitor in this market, Thermo Fisher Scientific appears to have exited the wider surface analysis market to focus strictly on its photoelectron spectroscopy products. Other market competitors include OCI Vacuum Engineering, VSW Atomtech and RBD Instruments, which released its most recent Auger product, the microCMA, about a year ago. The 2015 market demand for Auger spectroscopy systems was about $70 million.
Auger Electron Spectroscopy at a glance:
- Scienta Omicron
- Semiconductors and Electronics
- $250,000 to $1.5 million