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Characterization of Thin-Layer Materials by Auger Electron Spectroscopy (AES) Combined with Ion Etching

Marcin Pisarek 

Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
Polish Academy of Sciences, Institute of Physical Chemistry, Kasprzaka 44/52, Warszawa 01-224, Poland


Studies of the chemical and physical nature of passive oxide films formed on metals and alloys is a central subject of corrosion research. Passive oxide layers, typically 2-5 nm in thickness, protect many metals and alloys from an aggressive influence of the corrosion environment. Most of present knowledge on the chemical composition of passive films comes from ex-situ surface analytical methods. In particular AES (Auger Electron Spectroscopy) technique provide fundamental information on the chemical composition and state of components of thin surface layers, and particularly on surface atoms. AES is closely related technique which involve the energy of electrons emitted from small depth (several atomic layers) at the surface of a material. These fundamental information ensured the usefulness of AES for practical surface analysis. The composition surface layers is often quite different from that of the bulk material due to contamination, oxidation, or technological processing. This method give an insight into important problem concerning nature of passive films / oxide layer. Notable they provide an answer to the following question:
a) Which elements are present at the surface?
b) What is chemical state of these elements?
c) How much of each chemical state of each element is present?
d) What is the spatial distribution of the materials in three dimensions?
d) Is material present as a thin film at the surface?
- how thick is the film?
- how uniforms is its thickness?
- how uniform is the chemical composition of the film?
Many interesting information about structure and chemical composition of passive films / oxide layer can be obtained using combination of ion sputtering with AES method. Depth profiling is usually accomplished by inert gas (Ar+) ion bombardment to remove successive layers of materials from the surface. AES composition profiles are particularly useful since they can be acquired fast and with high depth resolution. Sputter profiling, however, damages the sputtered oxide films and can lead to composition changes by preferential sputtering and/or ion mixing.


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Presentation: Oral at E-MRS Fall Meeting 2006, Thin-layered materials workshop, by Marcin Pisarek
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-08-04 17:54
Revised:   2006-08-08 13:13