Influence of RF power on the properties of sputtered ZnO:Al thin films

Transparent conducting, aluminium doped zinc oxide thin films (ZnO:Al) were deposited by radio frequency (RF) magnetron sputtering. The RF power was varied from 60 to 350 W whereas the substrate temperature was kept at 160 degrees C. The structural, electrical and optical properties of the as-deposited films were found to be influenced by the deposition power. The X-ray diffraction analysis showed that all the films have a strong preferred orientation along the [001] direction. The crystallite size was varied from 14 to 36 nm, however no significant change was observed in the case of lattice constant. The optical band gap varied in the range 3:44-3.58 eV. The lowest resistivity of 1.2 x 10(-3) Omega cm was shown by the films deposited at 250W. The mobility of the films was found to increase with the deposition power. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim