A self-powered, visible-blind ultraviolet photodetector based on n-Ga:ZnO nanorods/p-GaN heterojunction

A self-powered visible-blind ultraviolet (UV) photodetector based on n-Ga:ZnO nanorods (GZO NRs)/p-GaN heterojunction was reported, in which the n-type GZO NRs were prepared by the water bath method. In this study, we found n-GZO NRs/p-GaN heterojunction devices showed better performance than those of n-ZnO NRs/p-GaN heterojunction devices in terms of the ratio Iph/Idark, responsivity and detectivity. Under UV illumination with the light intensity of 1.31 mW/cm2, the ratio Iph/Idark for the n-GZO NRs/p-GaN heterojunction was as high as 3.2 × 105 at zero bias, which is about 75 times greater than that of an un-doped device (only 4.2 × 103). Also its responsivity reached 0.23 A/W which was three times larger than that of n-ZnO NRs/p-GaN (∼0.08 A/W). The reason n-GZO NRs/p-GaN heterojunction displayed lager light/dark current ratio, higher responsivity and detectivity, and more reliable self-powered performance at zero bias may be that in GZO NRs, the Ga-doping reduced the defect states in the nanorods, enhanced the conductivity and electron mobility of the ZnO material and benefited the photo-generated carriers transmission.