Growth of V2O3 thin films on a-plane (110) and c-plane (001) sapphire via pulsed-laser deposition

We report the direct deposition of epitaxial 215-nm-thick vanadium sesquioxide (V2O3) films on a- and c-plane sapphire substrates from powder-pressed V2O3 targets via pulsed-laser deposition (PLD) in an evacuated deposition chamber devoid of O2. The films were characterized using x-ray diffraction (XRD), x-ray photoemission spectroscopy (XPS), x-ray absorption fine structure (XAFS) spectroscopy, and atomic force microscopy (AFM). XPS measurements confirmed that the stoichiometry of the powder was conserved in the films. XRD patterns together with XAFS measurements proved that V2O3 was epitaxial on the a-sapphire substrate with epitaxial relation (110)film//(110)substrate, and the results are consistent with the epitaxy on the c-plane substrate as well. The room-temperature resistivities of V2O3 films on a- and c-plane substrates were 1.49 x 10-4 and 3.00 x 10-5 O m, respectively. The higher resistivities of the films compared to bulk V2O3 might be attributed to thermal stresses resulting from difference in thermal expansion coefficients (TECs) of the films and the substrates.