Effect of growth temperature on structure and optical characters of NiO films fabricated by PA-MOCVD

We report the effect of growth temperature on structure, optical and electrical properties of NiO films fabricated by Photo-assisted Metal Organic Chemical Vapor Deposition (PA-MOCVD). It is found that the crystal quality of the NiO films has been improved by increasing the growth temperature. When the temperature is low, the NiO film is composed of small and anomalous grains, whereas the film is composed of grains with a cubic shape following the NaCl-type structure when the temperature is higher. The samples marked A–D under the growth temperature of 510, 540, 570 and 600 °C have optical band gap values of 3.93 eV, 3.82 eV, 3.73 eV and 3.55 eV, respectively. Comparatively, the controllable electrical properties of the films can be achieved by the variation of crystal quality arises from the growth temperature.

► NiO films were grown on sapphire substrates by Photo-assisted MOCVD.
► High crystal quality NiO films could be obtained at higher growth temperature.
► The resistivities of NiO films increased with increasing the growth temperature.
► The optical transmittances of NiO films were improved at higher growth temperature.