Molecular beam epitaxial growth of germanium and silicon films: Surface structure, film defects and properties

Abstract

Germanium and silicon films were grown on substrates of silicon (germanium and silicon films) and gallium arsenide (germanium films). Reflection high energy electron diffraction was used to investigate superstructure reconstructions on the growth surface as a function of the growth temperature and the film thickness. The greatest number of superstructures was observed during epitaxy of germanium films on Si(111): Si(7 × 7)Ge, Si,Ge(5 × 5), Ge(8 × 2), Ge(7 × 7)Si and Ge(1 × 1). The defects were studied in Ge/Si and Ge/GaAs heterosystems. The surface diffusion was found to have a marked effect on the film surface morphology and as a result of this on the type of misfit dislocations at the interface and on the density of threading dislocations. Electrophysical properties of the films are also discussed.