Investigation of halide vapor phase epitaxy of In2O3 on sapphire (0 0 0 1) substrates

Abstract The effect of the growth conditions on halide vapor phase epitaxy of In2O3 on sapphire (0001) substrates was investigated. Only the most thermally stable phase c-In2O3 grows at growth temperatures of 400 to 1000 °C. The growth rate increased as the growth temperature increased up to 700 °C, and layers with rough surfaces and a preferred (100) orientation were grown. Above 700 °C, the growth rate became constant, the preferential orientation changed to (111), and layers with smooth surfaces were grown. At 1000 °C, the volume fraction of the (111)-oriented domains in the grown layer reached 99.0%, although there were in-plane twins rotated by 180°. The growth rate also increased as the input partial pressure of the InCl or O2 source gas was increased, and a high growth rate exceeding 10 μm/h was found. The layer grown at 1000 °C was of high purity and incorporated no impurities other than Cl. Optical transmission measurements of this layer showed high optical transmittance at energies below the optical gap of 3.47 eV.