Effect of VI/III ratio on properties of alpha-Ga2O3 epilayers grown by halide vapor phase epitaxy

In this study, we report the effect of VI/III ratio on alpha-Ga2O3 epilayer on sapphire substrate by halide vapor phase epitaxy. The surface of alpha-Ga2O3 epilayer grown with various VI/III ratios was flat and crack-free. To analyze the optical properties of the alpha-Ga2O3 epilayers, the transmittance and an optical band gap were measured. The optical band gap was shown to be around 5 eV and showed a proportional increase in VI/III ratios. To determine the crystal quality of alpha gallium oxide grown with a ratio of 23, closed to the theoretical optical band gap, the FWHM was measured by HR-XRD. The calculated dislocation density of screw and edge were 1.5 x 10(7) cm(-2) and 5.4 x 10(9) cm (-2), respectively.