Paper TF-ThP24
Preparation of Very Thin GZO Transparent Electrodes with a Low Resistivity by a VAPE Method

Thursday, October 23, 2008, 6:00 pm, Room Hall D

Although transparent conducting impurity-doped ZnO thin films with a low resistivity have been prepared even on low temperature substrates, there is still a problem of the resistivity of the deposited films considerably increasing as the thickness is decreased, irrespective of the deposition methods used. This paper describes the improvements in the thickness dependence of resistivity as well as in other properties obtained in very thin low resistivity Ga-doped ZnO (GZO) thin films prepared using a newly developed vacuum arc plasma evaporation (VAPE) method. It should be noted that in film preparation by VAPE, the substrate normally must rotate or travel linearly during the deposition in order to improve distributions in film thickness and electrical properties across the substrate surface. In this work, however, the substrate remained fixed at a specific position during each deposition. The relative position between the flow direction of the arc plasma and the substrate surface and the VAPE method deposition conditions were optimized to further improve the thickness dependence of the resistivity in transparent conducting GZO thin films deposited on glass substrates. It was found that the obtained resistivity of GZO films deposited with a thickness below about 50 nm at a pressure of 0.15 Pa was strongly dependent on the substrate position relative to the arc plasma flow; it also was affected by the substrate temperature and the Ga content doped into deposited films. In addition, the obtainable resistivity is related to the crystallographical structure, crystallinity and surface morphology of deposited GZO thin films. A resistivity as low as 5X10^-4Ωcm was obtained in GZO thin films prepared with a thickness of approximately 30 nm under the optimized substrate position and deposition conditions.