Effect of thermal annealing on Ga-doped ZnO films prepared by magnetron sputtering

In this study, Ga-doped ZnO (GZO) films deposited on a sapphire utilizing magnetron cosputtering method using ZnO and Ga2O3 targets were demonstrated. The results revealed that the resistivities of the GZO films reduced by at least two orders of magnitude after the thermal annealing. The reduction in resistivity could be attributed not only to the activation of Ga dopants and to the increase of electron mobility, but also to the enlargement of the grain size that occurred as a result of thermal annealing. The resistivity of GZO films reduced from 1.4x10(-1) to 5.3x10(-4)Omega cm after the films had undergone thermal annealing in nitrogen ambience with temperature ranging from 400 to 800 degrees C. Additionally, the GZO films exhibited semiconducting conductivity and metallic conductivity in as-deposited and annealed samples (>600 degrees C), respectively. (c) 2007 The Electrochemical Study.