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

Indium gallium zinc oxide (In-Ga-Zn-O) thin films, which are transparent con-ductive 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 ox-ide. 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 tem-perature 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 In2O3/Ga2O3/ZnO composition in the powder target. The transmittances were symbolscript 75% at 800 nm for all the target mixtures, and increased with increasing In2O3 in the powder target.