Structure of single-crystal Gd_2O_3 films on GaAs (100)

摘要

We have studied the single-crystal Gd_2O_3 films grown epitaxially on GaAs (100) substrate with single-crystal x-ray diffraction. The sesquioxide Gd_2O_3 forms two hexagonal phases, one monoclinic and one cubic phase in bulk form. In our studies of different thickness films, we have found that the Gd_2O_3 grows only in the cubic phase with a unique epitaxial orientation. The two-fold (110) planes of the Gd_2O_3 are oriented parallel to the four-fold 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.