By using thermal Ge evaporation on GaAs(100), a study was made of the structural properties of these films as a function of the deposition rate. The film grain size and morphology exhibited a strong dependence upon the deposition rate. Low deposition rates resulted in films with large crystal grains and rough surfaces. At high deposition rates the films became flatter and their crystal grains size decreased, while at very high deposition rates films became amorphous. Cross-sectional TEM of the films showed that the Ge films were granular single crystal epitaxially grown on GaAs. The Ge/GaAs interface was atomically abrupt and free from misfit dislocations. Stacking faults along the [111] directions that originated at the interface were also observed. Finally by using the Kelvin probe microscopy it was shown that  work function changes were related to the grain structure of the film.

Structural Study of Ge/GaAs Thin Films. V.K.Lazarov, L.Lari, P.M.Lytvyn, V.V.Kholevchuk, V.F.Mitin: Journal of Physics - Conference Series, 2012, 371[1], 012040