Highly Visible-Blind ZnO Photodetector by Customizing Nanostructures With Controlled Defects

Abstract

In this work, a highly visible-blind UV photodetector with a large photo-responsivity using ZnO nanostructures is demonstrated. A large photoconductive gain of 2050 and external quantum efficiency of $2.05\times 10 ^{5}$ % at 350 nm (illumination intensity of 1 mW/cm2) incident radiation has been successfully achieved by morphological transition engineering i.e. growth of nanoplates around the nanorods. Further, by suppression of intrinsic defect states during the growth of nanostructures, high UV to visible rejection ratio of $4.78\times 10 ^{5}$ and photoresponsivity of 578 A/W has been accomplished. The device has demonstrated high selectivity for UV-A radiations, with a sharp responsivity peak at 350 nm of 60 nm FWHM. Moreover, the specific photo-detectivity was calculated to be as high as $2.15\times 10 ^{\mathbf {15}}$ cmHz $^{1/2}\,\,\text{W}^{-1}$ . The proposed device has the capability to establish ZnO as a potential candidate for the variety of commercial applications, where high responsivity along with large UV to visible rejection ratio are the major requirements.