Structural properties of zinc oxide thin films prepared by r.f. magnetron sputtering

ZnO thin films were deposited on sapphire, glass and silicon substrates by r.f. magnetron sputtering using metallic zinc target. A systematic study has been made of the influence of substrate temperature on the film structural properties. They exhibited a c-axis orientation of below 0.5° full width at half maximum of X-ray rocking curves, an extremely high resistivity of 1010 Ω cm and an energy gap of 3.3 eV at room temperature. It was found that a substrate temperature of 100 °C and target/substrate distance about 50 mm, very low gas pressures of 3.35×10−3 Torr in argon and oxygen mixed gas atmosphere giving to ZnO thin films a good homogeneity and a high crystallinity.