Pure-phase κ-Ga2O3 layers grown on c-plane sapphire by halide vapor phase epitaxy

Abstract κ-gallium oxide (Ga2O3) layers were hetero-epitaxially grown on c-plane sapphire substrates by halide vapor phase epitaxy (HVPE). Pure (001)-oriented κ-Ga2O3 with high crystal quality was obtained with this method on sapphire at 800 °C. Furthermore, three in-plane rotational domains in the κ-Ga2O3 layers on sapphire substrates were revealed by XRD ϕ-scan and two typical domain regions were observed by high resolution transmission electron microscopy with selected area electron diffraction. The in-plane epitaxial relationship was proposed to be (010) κ-Ga2O3//(10 1 ‾ 0) Al2O3 and (110) κ-Ga2O3//(1 1 ‾ 00) Al2O3. The bandgap was calculated to be ~5.02eV from the optical transmittance spectrum.