Epitaxial growth of phase-pure ε-Ga2O3 by halide vapor phase epitaxy

Epitaxial growth of ε-Ga2O3 is demonstrated for the first time. The ε-Ga2O3 films are grown on GaN (0001), AlN (0001), and β-Ga2O3 (2¯01) by halide vapor phase epitaxy at 550 °C using gallium chloride and O2 as precursors. X-ray ω-2θ and pole figure measurements prove that phase-pure ε-Ga2O3 (0001) films are epitaxially grown on the three kinds of substrates, although some minor misoriented domains are observed. High temperature X-ray diffraction measurements reveal that the ε-Ga2O3 is thermally stable up to approximately 700 °C. The optical bandgap of ε-Ga2O3 is determined for the first time to be 4.9 eV.