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.