Solution derived Al-doped zinc oxide films: doping effect, microstructure and electrical property

This study investigates the influences of the microstructures and doping effect on electrical and optical properties of ZnO:Al films deposited by sol-gel method. Experimental results showed that aluminum concentration affected the crystallite size obviously and enhanced the relative intensity i((002)) faintly. Based on photoluminescence results, too much doping atoms generally can cause film crystallinity to deteriorate. Hall measurements indicated the carrier concentration rose only to a certain level after several coating processes. According to ellipsometric data, higher carrier mobility was mainly caused by the escalating density resulted by the increasing film thickness. However, the formation mechanism of charge carrier by doping technique in the sol - gel process is different from that of sputtering technique. The best sample having a sheet resistance of 182 Omega/sq and a transmittance of over 80% in visible region was obtained in aluminum concentration of 1.0 at.%.