Fabrication of thin, dense and small-diameter zinc oxide nanorod array-based ultraviolet photoconductive sensors with high sensitivity by catalyst-free radio frequency magnetron sputtering

For the first time, thin, dense, and small-diameter zinc oxide (ZnO) nanorod arrays were deposited using catalyst-free radio frequency (RF) magnetron sputtering at a low power of 50 W for ultraviolet (UV) photoconductive sensor applications. The average diameter of the nanorod was approximately 15 nm with a length or thickness of 100 nm. By using 60 nm-thick aluminium (Al) to fabricate electrodes that were separated by different gaps of 0.07-2.00 mm, the UV photoconductive sensor exhibits considerable sensitivity up to 3008.3 at an inter-electrode gap of 2.00 mm, which is attributed to the high surface area provided by the large inter-electrode gap. However, the responsivity of the sensors decreased at large inter-electrode gaps. Our results demonstrate that high-performance UV photoconductive sensors could be realised using dense and thin sputtered ZnO nanorod arrays with small diameters. (C) 2012 Elsevier B.V. All rights reserved.