Growth mechanism and electronic properties of epitaxial In2O3 films on sapphire

In this work, we report on the epitaxial growth of high-quality cubic indium oxide thick films on c-plane sapphire substrates using a two-step growth process. The epitaxial relationship of In2O3 on (0001) Al2O3 has been investigated. The (222) plane spacing and lattice parameter of a most strain-relaxed high-quality In2O3 film have been determined to be 292.58 pm and 1013.53 pm, respectively. The electronic properties in dependence of the film thickness are interpreted using a three-region model. The density at the surface and interface totals (3.3±1.5)×1013cm-2, while the background electron density in the bulk was determined to be (2.4±0.5)×1018cm-3. Furthermore, post treatments such as irradiation via ultraviolet light and ozone oxidation have been found to influence only the surface layer, while the bulk electronic properties remain unchanged.