In-plane orientation control of (001) κ-Ga_2O_3 by epitaxial lateral overgrowth through a geometrical natural selection mechanism

摘要

Vapor phase growth ofc-plane kappa-Ga2O3 films has been reported on various substrates such as sapphire, GaN, and AlN. However, these films are not single crystalline, but rather a mixture of nanometer-sized in-plane 120 degrees rotational domains. We demonstrate a technique that solves the in-plane rotational domain problem. kappa-Ga2O3 was grown by epitaxial lateral overgrowth. A SiO(x)mask with a striped or dotted-striped pattern was aligned on ac-plane sapphire substrate with a TiOx buffer layer so that the stripe was parallel to the [112 over bar 0 kappa-Ga2O3 was then grown on the substrate by halide vapor phase epitaxy. Electron backscatter diffraction, X-ray diffraction, transmission electron microscopy, and selective area electron diffraction revealed that the three in-plane orientations of the kappa-Ga2O3 domains converged into one whose [010] direction was perpendicular to the stripe. The convergence occurred through a geometrical natural selection mechanism.