Fast response ZnO:Al/CuO nanowire/ZnO:Al heterostructure light sensors fabricated by dielectrophoresis

Metal oxide nanowire (NW) photoconductors tend to exhibit high photoconductive gains and long recovery times mainly due to surface effects. In this work, p-type CuO NWs are synthesized by direct oxidation of copper and deposited on n-type ZnO:Al electrodes by dielectrophoresis. The heterostructure is electro-optically characterized showing recovery times in the 10 mu s range, mainly limited by the resistance-capacitance product of the equivalent circuit, without signs of persistent effects. The fast response is attributed to short transit times across space charge regions built between CuO and ZnO:Al materials and fast carrier recombination at neutral regions. (C) 2013 AIP Publishing LLC.