Common semiconducting metal oxide thin films include ITO (indium-tin oxide) thin films, ATO (aluminum-tin oxide) thin films, and AZO (aluminum-zinc oxide) thin films. Recently, increasing research interest on the AZO thin films is not only due to the low resistivity, but also the optical characteristics. AZO thin film exhibits a sharp UV cut-off and a high refractive index in the IR range, and is transparent in the visible light. The objective of this study was then to investigate the electrical and optical properties of AZO as a function of various growth parameters, including target composition, O-2/Ar ratio, and applied power. The crystal structure was found to be insensitive to oxygen partial pressure but affected by the doping of Al. However, the values of resistivity depend on both the oxygen partial pressure and the Al doping level.