Growth and Characterization of α-, β-, and ε-Ga2O3 Epitaxial Layers on Sapphire

This study reports on the growth and characterization of three different phases - alpha, beta, and epsilon - of Ga2O3 epitaxial layers grown on (001) sapphire substrates at 650 degrees C. The stable beta-phase was observed for films grown using metalorganic chemical vapor deposition with trimethygallium and oxygen as source gases. In contrast, the alpha- and/or epsilon-phase(s) were observed for films grown by halide vapor phase epitaxy with gallium chloride and oxygen as source gases. Orientation relationships from x-ray diffraction measurements are reported, along with transmission electron microscopy images of the interfacial microstructure and optical transmittance measurements of the different phases.