Characterization of iron-silicon thin films by means of electron diffraction and X-ray spectroscopy

Iron-silicon thin films have been characterized by means of analytical transmission electron microscopic methods. Under certain conditions — composition and annealing temperature — these films exhibit thermoelectric behavior. In particular, the morphology and phase formation which results from annealing of these films, and doping with oxygen and nitrogen, are of interest. The thermoelectric phase -FeSi₂ is formed at temperatures above 500°C. This phase is transformed into electrically conducting phases at about 1000°C. A small oxygen content does not influence this crystallization process. If the oxygen content is higher than 15 atom-% the electrically conducting phases exist even at 500°C. The presence of a small nitrogen content inhibits the formation of the -FeSi₂ phase. The development of silicon and iron nitrides is possible.