Electrical, structural, and optical properties of Cr-doped and non-stoichiometric V2O3 thin films

V2O3 films and Cr-doped V2O3 films were grown on (0 0 0 1) (C-plane) and (1 1 2¯ 0) (A-plane) oriented sapphire substrates by the reduction of sol–gel derived vanadium oxide films. Examination by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy showed the films to be comprised of highly oriented grains. Optical transmission and resistivity measurements revealed phase transitions characteristic of the single crystal V2O3 and Cr-doped V2O3. Subsequent anneals of the un-doped films under controlled oxygen atmospheres yielded non-stoichiometric films with metal-insulator transitions characteristic of annealed V2O3 single crystals.