Effects of substrate and ambient gas on epitaxial growth indium oxide thin films

•Epitaxial indium oxide thin films were grown on sapphire and LaAlO3 single crystal substrates.•Stoichiometric In2O3 films are formed under oxygen.•Nanocomposite In2O2.5 films are formed under argon ambient.•Various orientation relationships depend on the substrate symmetry and gas ambient.•Domain matching epitaxy describes the in-plane epitaxial relationships. Indium oxide thin films were grown by pulsed electron beam deposition method at 500°C on c-cut sapphire and (001) oriented LaAlO3 single crystal substrates in oxygen or argon gas. The effects of ambient gas and substrate symmetry on the growth of indium oxide thin films were studied. Stoichiometric In2O3 films are formed in oxygen, while oxygen deficient In2O2.5 films are grown in argon, with In metallic nanoclusters embedded in a In2O3 matrix (nanocomposite films). In both cases, epitaxial In2O3 films having the bixbyite phase were grown with various orientation relationships, depending upon the substrate symmetry and gas ambient (oxygen or argon). Domain matching epitaxy was used to describe the precise in-plane epitaxial film–substrate relationships. The differences in film texture were correlated to the differences in growth conditions, while the differences in the film properties were correlated to the film oxygen composition.