Ya-Qing Bie, Zhi-Min Liao, Hong-Zhou Zhang, Guang-Ru Li, Yu Ye, Yang-Bo Zhou, Jun Xu, Zhi-Xin Qin, Lun Dai, Da-Peng Yu

In the past few years, a mass of experiments have been conducted focusing on the ultraviolet (UV) photodetection using ZnO nanowires. However, due to the presence of carrier depletion layer at the nanowire surface caused by surface trap states, the recovery time of the photodetector based on the variation of ZnO nanowire photoconductivity is longer than 1 second. In this work, by constructing the heterojunctions based on single n-type ZnO nanowire and p-type GaN film, we demonstrate self-powered visible-blind UV detectors with ultrafast response of rise time (~20 μs) and decay time (~219 μs), which is two orders of magnitude faster than the ZnO photoconductivity based photodetectors. The UV detectors were driven by the photovoltaic effect of the ZnO/GaN p-n junction with short-circuit current density up to ~ 5×10⁴mA cm^-2, open-circuit voltages ~ 2.7 V, and maximum output power ~ 1.1 μW. Furthermore, a multi-wavelength photodetector was fabricated by integrating the PV device with a CdSe nanowire red-light detector. The integrated nanocircuit functioned as an optical AND logic gate and operational multi-states output was also demonstrated.

Advanced Materials, 2010:http://dx.doi.org/10.1002/adma.201003156