Epitaxial growth of wide-band-gap ZnGa2O4 films by mist chemical vapor deposition

ZnGa2O4 films were grown on (100) MgAl2O4 substrates by mist chemical vapor deposition. A growth window for obtaining single spinel phase was revealed by systematic variations of precursor Zn/Ga ratio and growth temperature, where the cation stoichiometry was maintained through sublimation of excess Zn species before crystalized into ZnO. The epitaxial relationship to the substrate was identified to be cube on cube with no rotation domain. The optical properties of the fully relaxed film were characterized by using cathodoluminescence (CL) and absorption spectroscopies. A large Stokes shift was found between the CL peak energy (3.4 eV) and fundamental absorption edge (4.6 eV), reflecting typical property of Ga-based wide-band-gap oxide semiconductors.