G.A. Hirata, J. McKittrick, O.A. Lopez and M. Avalos-Borja, "Thin Conductive Gallium Doped Zinc Oxide Grown by Pulsed Laser Deposition," Journal of the Society for Information Display, 4 [4] 343-345 (1996).

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 W/sq. were measured on films with thicknesses of 200 nm deposited on glass at 300°C. From opto-electronic measurements we observed a good gallium-doping efficiency and a widening of the bandgap when varying the substrate temperature from 150°C 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.