Halide vapor phase epitaxial growth of β-Ga2O3 and α-Ga2O3 films

Abstract

Halide vapor phase epitaxy was used to grow homoepitaxial films of β-Ga2O3 on bulk (010) crystals and heteroepitaxial films of α-Ga2O3 on c-plane sapphire substrates. The β-Ga2O3 substrates were prepared prior to growth to remove sub-surface damage and to apply various miscuts to their surfaces. Structural and electrical properties were found to be most impacted by the crystallinity of the β-Ga2O3 substrate itself, while the surface morphology was found to be most impacted by the miscut of the substrate. The appropriate choice of growth conditions and the miscut appear to be critical to realizing smooth, thick (>20 µm) homoepitaxial films of β-Ga2O3. The α-Ga2O3 films were grown on commercially available c-plane sapphire substrates, and the film morphology was found to be strongly impacted by the surface finish of the sapphire substrates. The α-Ga2O3 films were found to be smooth and free of additional phases or crystal twinning when the sapphire was sufficiently polished prior to growth.