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

Epitaxial growth of epsilon-Ga2O3 is demonstrated for the first time. The epsilon-Ga2O3 films are grown on GaN (0001), AlN (0001), and beta-Ga2O3 ((2) over bar 01) by halide vapor phase epitaxy at 550 degrees C using gallium chloride and O-2 as precursors. X-ray omega-2 theta and pole figure measurements prove that phase-pure epsilon-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 epsilon-Ga2O3 is thermally stable up to approximately 700 degrees C. The optical bandgap of epsilon- Ga2O3 is determined for the first time to be 4.9 eV. (C) 2015 AIP Publishing LLC.