Aluminum doped ZnO thin films by RF sputtering of coaxial ZnO and Al targets

Abstract

Transparent conducting aluminum doped zinc oxide (AZO) films were deposited on glass substrates by radio (RF) frequency magnetron sputtering employing zinc oxide and aluminum targets. The targets are fixed coaxially in one cathode, by using a center hollow aluminum disc. Gas pressure was kept constant and the sputter power was varied. The nature of AZO film was found to be polycrystalline with hexagonal structure and a preferred orientation along c-axis. The Al content in the films is determined using EDXA analysis and it is found to vary with the applied power. Surface morphology of the films was found to be uniform and has fine grained structure. Electrical resistivity of the deposited films was found to be as low as 26�10-4?-cm for the film deposited at 250 W. The average transparencies up to 85% in the visible region were obtained for all the films. Optical band gap of the films show a slight blue shift as indicated by the (?h?)2 v/s h? plots. In the present investigation we have controlled Al content in the films by adjusting the power to the coaxial targets. The value of resistivity was found to decrease with the amount of Al present in the sample. � 2011 American Institute of Physics.