Al-reactions with GaAs (100) surfaces

The interactions of epitaxial Al-films with GaAs (100) surfaces, prepared by molecular beam epitaxy, have been investigated using a variety of surface sensitive techniques: Auger electron spectroscopy, electron energy-loss spectroscopy and reflection high energy electron diffraction. Depending on the substrate temperature, two entirely different reactions are observed, which result in two different crystallographic orientations of the Al-film. At elevated temperature a Ga-Al exchange reaction, similar to that reported for Al on the GaAs (110) surface, takes place. However, with the substrate near room temperature no evidence for such a reaction is found. The results are substantiated by comparison with measurements on thin Ga overlayers on AlAs, prepared to simulate surfaces with exchange reaction geometry. © 1981.