Influence of the annealing temperature on the self-powered CuO/ZnO NRs heterojunction photodetector

The CuO/ZnO NRs heterojunctions were grown using a hydrothermal method to prepare ZnO NRs and a spin coating technique to deposit CuO thin film. The samples were subjected to annealing treatment at varying temperatures (400, 500, and 600 °C) to study the effect of temperature on their structural, optical, and electrical characteristics. The samples were characterized by SEM, EDX, XRD, and UV–Vis. Spectra, also I–V characteristic, and I-t in the dark and under UV illumination (385 nm and 405 nm). On fabricating photodetectors, the 400 °C annealed CuO/ZnO NRs heterojunction sample has the highest photoresponse ratio (Iph/Idark) of 26.3 and highest photosensitivity (Sph%) 2531.6 through UV illumination 405nm and fast response time of 0.8 s at zero biasing, enhancement in crystallinity (as established from X-ray diffraction and SEM analysis respectively) in addition to efficiently separated photocarrier generation. This signified that the annealing temperature on the CuO/ZnO NRs heterojunction has an attractive scope for photodetector application.