Thin conductive gallium-doped zinc oxide grown by pulsed laser deposition

A new process to prepare ZnO:Ga thin conductive oxide (TCO) films with excellent optical and electrical properties is described in this work. The Ga-doped ZnO targets used for thin-film deposition were prepared from powder materials obtained with a novel ceramic processing technique (combustion synthesis). The deposition of the ZnO:Ga thin films was performed on glass at different substrate temperatures (150-300°C) in an ultra-high-vacuum laser ablation system. High transmittance (>85%) of light in the visible range and sheet resistance values as low as 18 Ω?. were measured on films with thicknesses of 200 nm deposited on glass at 300°C. From optoelectronic measurements we observed a good gallium-doping efficiency and a widening of the bandgap when varying the substrate temperature from 150 to 300°C, in good agreement with other work. X-ray diffraction and high-resolution transmission electron microscopy measurements revealed that the films grow preferentially oriented in the (002) crystallographic direction of the ZnO grains.