Sensitivity Enhancement of Ultraviolet Photodetectors With the Structure of p-NiO/Insulator-SiO 2 /n-ZnO Nanowires

A high-performance photodetector with the structure of NiO/SiO2/ZnO nanowires has been proposed. The devices with 6-nm-thick SiO2exhibited a better rectification ratio (Jforward/Jreverse) of 246 at ±2 V, lower dark current density (Jdark) of 3.5 × 10-7A/cm2at a reverse bias of 2 V, and superior ultraviolet (UV) sensitivity (IUV/Idark) of 16.23 than those without the SiO2layer (Jforward/Jreverse= 44, Jdark = 4.7 × 10-6A/cm2, and IUV/Idark = 5.5). The improved performance was mainly due to the ultrathin inserted SiO2layer that builds a barrier height to minimize the transmission probability of low-energy carriers, leading to the enhancement of the UV sensing characteristics.