Preparation of transparent and semiconducting NiO films

Effect of annealing in the structure and morphology of vacuum deposited thin nickel films are reported. From the Xray diffraction analysis, the oxidation mechanism observed in the transformation of Ni to NiO suggested that the phase transformation could occur through two oxidation states. The SEM observations indicate that the oxidation of Ni to NiO is controlled by the diffusion of Ni ions through the grain boundaries. A needle-type growth seen at some regions of the films annealed in the range 573-623K is also reported. A maximum transparency of 75% at 550nm and an optical band gap of 3.54eV are obtained for the NiO film and its temperature coefficient of resistivity is found to be negative in the range 303-468 K. (C) 2002 Elsevier Science Ltd. All rights reserved.