Enhancement in ZnO-based self-powered photodetector by inserting Mn dopant

In this study, the effect of Mn doping on the photovoltaic properties of ZnO films deposited on a p-Si substrate via spray pyrolysis has been evaluated. The Mn concentration was varied at 0, 1, and 3 wt%. The spray was carried out at 400 °C for 10 min. As a result, the X-ray diffraction pattern shows that the crystallite size decreases linearly with increasing Mn doping, from 44 nm (0% Mn) to 31 nm (3% Mn). Scanning electron microscopy images show that the increase in Mn concentration causes the nanostructure size to be smaller, from 325 nm (0% Mn) to 112.3 nm (3% Mn). Interestingly, the best photosensitivity and response time are found in the doped sample (3% Mn) at a bias voltage of 0 V rather than 1 V and 5 V, indicating the photovoltaic effect. This result is important to develop future self-powered devices.