Growth and crystal phase transformation of ε-Ga2O3 grown on 4H–SiC by MOCVD

Abstract

Ga2O3 thin films were hetero-epitaxially grown on 4H–SiC substrates by metal-organic chemical vapor deposition (MOCVD) under various growth conditions. The growth process and crystal quality of the ε-Ga2O3 thin films grown on C-face and Si-face of 4H–SiC substrates were compared. The ε-Ga2O3 film grown on a Si-face substrate shows better performance in improving crystal quality compared to the case of growth on a C-face. A ε-Ga2O3 thin film grown at 665 °C with an H2O flow rate of 200 sccm was thermally annealed at 900 °C for 10 min in an oxygen atmosphere for a crystal phase transformation to a β-Ga2O3 thin film. The RMS roughness of the transformed β-Ga2O3 thin film was 9.023 nm while the RMS value of directly grown was 129.1 nm. The estimated screw and edge dislocation density of the ε-Ga2O3 thin film were 1.41 × 1013 cm−2 and 4.92 × 1012 cm−2 respectively. Transformation of the crystal phase from ε-Ga2O3 to β-Ga2O3 can be considered as an effective method in hetero-epitaxial growth of Ga2O3 on SiC substrate.