Indium-gallium-zinc oxide thin-film preparation via single-step radio frequency sputter deposition using mixed-oxide powder targets

Abstract

: Indium gallium zinc oxide (In–Ga–Zn–O) thin films, which are transparent conductive films for liquid crystals and electroluminescent displays, were fabricated via single-step sputter deposition using one target containing different proportions of indium oxide, gallium oxide, and zinc oxide powders. Experimental results suggest that the In–Ga–Zn–O thin films can be prepared using the method of single-step radio frequency (RF) sputter deposition, applying a powder target containing indium oxide, gallium oxide, and zinc oxide. The In–Ga–Zn–O thin films were prepared on Si substrates, and the deposition rate depended on the target composition. In these plasma processes, electron density and temperature were essentially independent of target composition. The prepared films were very smooth with a root-mean-square roughness of less than 10 nm. The crystallinity of the ZnO peak was observed in all the films; whereas the In and Ga peaks were not observed in the films prepared. The X-ray photoelectron spectroscopy of the films also revealed that the elemental concentration ratio of In–Ga–Zn–O thin films could be prepared using one target, and that can be easily controlled by ratios in the In 2 O 3 /Ga 2 O 3 /ZnO composition in the powder target. The transmittances were > 75% at 800 nm for all the target mixtures, and increased with increasing In 2 O 3 in the powder target.