Sensitivity Enhancement of Ultraviolet Photodetectors With the Structure of p-NiO/Insulator-SiO2/n-ZnO Nanowires

Abstract

A high-performance photodetector with the structure of NiO/SiO2/ZnO nanowires has been proposed. The devices with 6-nm-thick SiO2 exhibited a better rectification ratio (J(forward)/J(reverse)) of 246 at +/- 2 V, lower dark current density (J(dark)) of 3.5 x 10(-7) A/cm(2) at a reverse bias of 2 V, and superior ultraviolet (UV) sensitivity (I-UV/I-dark) of 16.23 than those without the SiO2 layer (J(forward)/J(reverse) = 44, Jdark = 4.7x10(-6) A/cm(2), and I-UV/I-dark = 5.5). The improved performance was mainly due to the ultrathin inserted SiO2 layer that builds a barrier height to minimize the transmission probability of low-energy carriers, leading to the enhancement of the UV sensing characteristics.