Epitaxial growth of ?-Ga2O3 thin films on SrTiO3 (111) and (100) substrates by chemical vapor deposition

Due to good lattice matching and bipolar doping behavior, wide bandgap SrTiO3 (STO) is a promising substrate for the heteroepitaxial growth of beta-Ga2O3 to construct heterojunctions for (opto-)electronic device applications. However, the investigation of the growth of beta-Ga2O3 film on the STO (111) substrate is still lacking. In this work, for the first time, the beta-Ga2O3 (2 01) thin films were epitaxially grown on the supercell matched STO (111) substrates by low pressure chemical vapor deposition. The effects of the source and growth temperatures on the surface roughness and crystalline quality of the beta-Ga2O3 films were systemically investigated. By controlling the supply of Ga source, the heteroepitaxial beta-Ga2O3 film grown under the optimized conditions exhibits a narrow X-ray diffraction rocking curve of 0.75 degrees and a low root-mean-square roughness of 1.10 nm. Furthermore, the epitaxial growth of beta-Ga2O3 films on the STO (10 0) substrate was also investigated. The heteroepitaxy of beta-Ga2O3 films on STO lays the foundation for future device applications of beta-Ga2O3-based heterojunctions.