Enhanced Visible-Light Photodetection with Undoped and Doped ZnO Thin-Film Self-Powered Photodetectors.

Photodetection plays an essential role in the visible-light zone and is important in modern science and technology owing to its potential applications in various fields. Fabrication of a stable photodetector remains a challenge for researchers. We demonstrated a high-response/recovery and self-powered undoped ZnO (UZO) and Cu-doped ZnO (CZO) thin film-based visible-light photodetector fabricated on a cost-effective Si substrate using reactive cosputtering. The structural, morphological, and optical properties of CZO and UZO thin films have been examined using X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and photoluminescence spectroscopy. The results of the CZO/n-Si photodetector compared with those of the undoped ZnO (UZO)/n-Si photodetector show that the CZO/n-Si exhibits a higher on/off ratio, responsivity, and detectivity than UZO/n-Si. Also, the CZO/n-Si photodetector shows high stability and reproducibility over 20 cycles after 180 days. A relative study of CZO/n-Si- and UZO/n-Si-based photodetectors reveals the enhanced performance of the CZO/n-Si photodetector, which has a high on/off ratio of ∼300 with a high specific detectivity of 2.8 × 1010 Jones for 75 mW visible light. The prepared self-powered CZO/n-Si/Ag thin film-based visible-light photodetector paves the way for the development of high-performance photodetector designs.