High-performance UV detector made of ultra-long ZnO bridging nanowires.

A nanowatt UV photoconductive detector made up of ultra-long (approximately 100 microm) ZnO bridging nanowires has been fabricated by a single-step chemical vapor deposition (CVD) process. The electrodes, forming comb-shaped thick ZnO layers, and the sensing elements, consisting of ZnO nanowires bridging the electrodes, were fabricated simultaneously in a single-step CVD process. The device showed drastic changes (10-10(5) times) in current under a wide range of UV irradiances (10(-8)-10(-2) W cm(-2)). Moreover, the detector exhibited fast response (rise and decay times of the order of 1 s) to UV illumination in air, but no response to visible light (hnu<3.2 eV). Our approach provides a simple and cost-effective way to fabricate high-performance 'visible-blind' UV detectors.