This study reports on the growth and characterization of three different phases -α, β, and ε -of Ga 2 O 3 epitaxial layers grown on (001) sapphire substrates at 650 °C. The stable β-phase was observed for films grown using metalorganic chemical vapor deposition with trimethygallium and oxygen as source gases. In contrast, the αand/or ε-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.