Photoconductivity of vertically aligned ZnO nanoneedle array

Abstract

A high-density vertically well-aligned ZnO nanoneedle array was fabricated on a ZnO-buffer film on silicon substrates by metal-organic chemical vapor deposition at a growth temperature of 480–500°C. Highly crystalline ZnO nanoneedle arrays showed a strong near-bandedge emission at 380nm in room-temperature photoluminescence. A simple ultraviolet (UV) sensor was fabricated by evaporating a Ag electrode on the ZnO nanoneedle array. The photoresponse results showed very high photocurrent (∼10−4A) from ZnO nanoneedles compared to a single-nanowire sensor (∼10−8A), indicating high sensitivity of the photosensor. It also showed fast rise and decay times in UV-on/off switching measurements.