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

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