Heteroepitaxial growth of ε-Ga₂O₃ thin films on cubic (111) MgO and (111) yttria-stablized zirconia substrates by mist chemical vapor deposition

Abstract

Abstract In this study, epitaxial ε-Ga 2 O 3 thin films are successfully grown on cubic (111) MgO and (111) yttria-stablized zirconia (YSZ) substrates by mist chemical vapor deposition. Pure-phase hexagonal ε-Ga 2 O 3 thin films are grown on the two substrates with a c -axis orientation determined by X-ray diffraction (XRD) 2θ–ω scanning. XRD pole figure measurements reveal that the in-plane orientation relationship between the (0001) of ε-Ga 2 O 3 and the (111) of the two substrates is ε-Ga 2 O 3 ∥ substrates . Using (111) MgO substrates with a 2.5% lattice mismatch, the epitaxial ε-Ga 2 O 3 films are successfully grown at a low temperature of 400 °C. The optical direct and indirect bandgaps of pure ε-Ga 2 O 3 thin films are estimated as 5.0 and 4.5 eV, respectively.