Optimization of sputtering parameters for deposition of Al-doped ZnO films by rf magnetron sputtering in Ar + H2 ambient at room temperature

The effects of sputtering pressure and power on structural and optical-electrical properties of Al-doped ZnO films were systemically investigated at substrate temperature of room temperature and H-2/(Ar+H-2) flow ratio of 5%. The results show that carrier concentration and mobility of the films show nonmonotone change due to the evolution of microstructure and lattice defect of the films caused by introduction of H-2 with increasing sputtering pressure and power. The transmittance of the films is also found to be related to the introduction of H-2 in addition to usually considered surface roughness and crystallinity. Finally, optimized sputtering pressure and power are 0.8 Pa and 100 W, respectively, and obtained minimum resistivity and highest transmittance are 1.43x10(-3) Omega.cm and 90.5%, respectively. In addition, it is found that E-g of the films is mainly controlled by the carrier concentration, but crystallite size and stress should also be considered for the films deposited at different powers. (C) 2012 Elsevier B.V. All rights reserved.