Structure of Single-Crystal Gd2O3Films on GaAs(100)

Abstract

ABSTRACTWe have studied the single-crystal Gd2O3films grown epitaxially on GaAs(100) substrate with single-crystal x-ray diffraction. The sesquioxide Gd2O3forms two hexagonal phases, one monoclinic and one cubic phase in bulk form. In our studies of different thickness films, we have found that the Gd2O3grows only in the cubic phase with a unique epitaxial orientation. The two-fold (110) planes of the Gd2O3are oriented parallel to the four-fold GaAs(100) surface, while alligning its [001] and [110] axes with the [011] and [011] axes of GaAs within the plane, respectively. The film chooses only one of the two such possible orientations, which can be explained by the local bonding configuration at the interface. We find evidence for an elastic strain in the films less than 50 A thick.