Structural effect on UV emission properties of high-quality ZnO thin films deposited by RF magnetron sputtering

Zinc oxide (ZnO) thin films were deposited on SiO2/Si(1 0 0) substrates by reactive RF magnetron sputtering technology. The effects of sputtering parameters on the crystalline and luminescent characteristics of ZnO films were investigated. According to the results, the optimal sputtering parameters for the best photoluminescence (PL) characteristics were found to be oxygen concentration, (O-2/O-2 + Ar), of 21%, RF power of 100W, substrate temperature of 500 degrees C and sputtering pressure of 5mTorr. The obtained wavelength of light emission was found at 379nm (ultraviolet-UV region), which may be due to the band-to-band transition. However, the optimal parameters for the best PL characteristics of ZnO thin films were not consistent with those obtained from the (002) intensities of XRD analyses. As a result, XRD pattern was not considered as the key issue concerning the intensity of PL of ZnO thin film. The intensity of the emitted UV light will correspond to the grain size of ZnO film. (c) 2007 Elsevier B.V. All rights reserved.