Photo detector fabrication based ZnO nanostructure on silicon substrate

Abstract

A photo detector was fabricated based on ZnO nanorods (NRs) on silicon substrate. The ZnO nanostructures were synthesized via hydrothermal method. The structure, morphology, and optical properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and UV–Visible spectrophotometer. XRD result, shows that the ZnO NRs is a hexagonal Wurtzite structure with preferred orientation (002) along the c-axis and the SEM photographs illustrate the average diameter and length of the ZnO nanorods were around 400 nm and 4 μm, respectively. The detector measurements revealed that the current–voltage characteristics of the ZnO NRs are asymmetrical, showing rectifying, diode-like behavior and the asymmetry factors (Id/Iph) about 13 at 5 V bias voltage was obtained. It was found that the, current under illumination was almost much higher compared with the dark current at − 5 V. The ZnO nanorods seem to be promising materials for high responsivity photo detector about 0.25 A/W and 0.29 A/W at 390 nm by applying a bias voltage of 0.5 V and 1 V respectively, with maximum quantum efficiencies of ZnO NRs 79% and 92% at the same bias voltage, which provides a route to fabricate a good UV photo detector.