Growth of twin-free cubic In2O3(111) thick layers on c-plane sapphire substrates by halide vapor phase epitaxy

The growth of twin-free single-crystal cubic-indium oxide (c-In2O3) layers was investigated by halide vapor phase epitaxy on c-plane sapphire substrates with various off-axis angles. The growth rate of the c-In2O3 layer increased and twin formation was suppressed as the off-axis angle of the substrate was increased. A single-crystal c-In2O3(111) layer grown on a sapphire substrate with a 5° off-axis angle showed a room temperature carrier density and mobility of 1.4 × 1016 cm−3 and 232 cm2 V−1 s−1, respectively. Temperature-dependent Hall measurements of the layer revealed that the mobility is dominated by optical phonon scattering.