Growth of In2O3(111) thin films with optimized surfaces

Indium oxide is widely employed in applications ranging from optoelectronics and gas sensing to catalysis, as well as in thin-film heterostructures. To probe the fundamentals of phenomena at the heart of In2O3-based devices that are tied to the intrinsic surface and interface properties of the material, well-defined single-crystalline In2O3 surfaces are needed. We report on how to grow atomically flat In2O3(111) thin films on yttria-stabilized zirconia substrates by pulsed laser deposition. The films are largely relaxed and reproduce the atomic-scale details of the surfaces of single crystals, except for line defects originating from the antiphase domain boundaries that form because of the one-on-four lattice match between the surface unit cells of In2O3(111) and of the substrate. While optimizing the growth conditions, we observe that the morphology of the films is ruled by the oxygen chemical potential, which determines the nature and diffusivity of adspecies during growth.