Ultraviolet photodetector based on heterojunction of n-ZnO microwire/p-GaN film

High quality ZnO microwires have been fabricated by chemical vapor deposition method. Ultraviolet photodetector based on heterojunction of n-ZnO (individual microwire)/p-GaN film was fabricated. The current-voltage characteristic of the photodetector was investigated, which showed that the heterojunction had rectifying behavior with rectification ratio (I-forward/I-reverse) of about 6.3 x 10(2) at 4 V. The photoresponse spectrum displayed a sharp cut-off at the wavelength of 380 nm, and the photoresponsivity was as high as 0.45 A W-1 at 0 V and 1.3 A W-1 at 2.5 V reverse bias. The ultraviolet-visible rejection ratio (R370 nm/R450 nm) is three orders of magnitude under zero bias.