We demonstrated a crack-free α-Ga2O3 on sapphire substrate by horizontal halide vapor phase epitaxy (HVPE). Oxygen-and gallium chloride-synthesized Ga metal and HCl were used as the precursors, and N2 was used as the carrier gas. The HCl flow and growth temperature were controlled in the ranges of 10~30 sccm and 450~490℃, respectively. The surface of α-Ga2O3 template grown at 470℃ was flat and the root-mean-square (RMS) roughness was ~2 nm. The full width at half maximum (FWHM) values for the symmetric-plane diffractions, were as small as 50 arcsec and those for the asymmetric-plane diffractions were as high as 1,800 arcsec. The crystal quality of α-Ga2O3 on sapphire can be controlled by varying the HCl flow rate and growth temperature.
