High Spectrum Selectivity Ultraviolet Photodetector Fabricated from an n-ZnO/p-GaN Heterojunction

Undoped n-ZnO films have been deposited onto p-GaN to form a pn heterojunction, and the current−voltage curve of the heterojunction shows obvious rectifying behaviors. A photodetector is fabricated from the heterojunction. Under back-illumination conditions, the GaN layer on one hand acts as a p-type counterpart for the n-ZnO layer, on the other hand as a “filter” that is transparent to the illumination light with wavelength longer than 360 nm. Because of the GaN “filter”, the photodetector shows a narrow band-pass response of only 17 nm in width. The results reported in this paper may provide a facile route to photodetectors with high spectrum selectivity.