MOCVD growth of Si-doped α-(AlGa)2O3 on m-plane α-Al2O3 substrates

Abstract

We reported the growth of (AlGa)2O3 layers on (10 10̅ ) α-Al2O3 substrates using cold-wall metalorganic chemical vapor deposition, and the electrical characterization of Si-doped (AlGa)2O3 layers. In the Ga2O3 growth, the α phase was dominant at low growth temperature, achieving the growth rate of 2.4 μm h−1 at 650 °C. Sheet resistance and electrical conductivity of the Ga2O3 layers with a Si concentration of 3 × 1020 cm−3 were 1 × 104 Ω/square and 8.3 S cm−1, respectively, at the measurement temperature of 500 °C. The Al composition in the (AlGa)2O3 layers was controlled from 0% to 74%. In our initial attempts, we obtained electrically conductive α-(AlGa)2O3 layers by Si doping (2 × 10−9 S cm−1 in the sample with an Al composition of 56%). Hybrid functional calculations suggest the conductivities are limited by compensation of Si through cation vacancy complexes, and not by the significant amounts of co-incorporated C and N that are predicted to be electrically passivated by hydrogen.