Study of ZnO/NiO Self-Powered UV–visible Broadband Photodetector with MgO Interfacial Layer and Silver Nanoislands in PIN Configuration

Abstract

Ultraviolet (UV)–visible self-powered photodetectors (PDs) are attractive for next-generation optoelectronic applications. The performance is often limited by interfacial carrier recombination and inefficient light absorption within the active layer. An interfacial layer with plasmonic nanoislands incorporation provides an effective route to enhance charge transport and light-matter interaction. In this study, ZnO/NiO, ZnO/MgO/NiO, and ZnO/MgO/Ag-NIs/NiO PDs were developed using pulsed laser deposition to examine the influence of interfacial engineering and plasmonic enhancement on sensitivity, stability, and response time. Silver nanoislands (Ag-NIs) and a Magnesium Oxide (MgO) interfacial layer at the ZnO/NiO junction significantly improve device performance in both biased and self-powered operation. Under 365 nm illumination, the responsivity increases from 0.53 A/W for the ZnO/NiO device to 3.01 A/W with the MgO interlayer, and further to 4.4 A/W after incorporating Ag-NIs. The device based on Ag-NIs has a visible-light responsivity which is up to 140 times higher than the device without Ag-NIs. The specific detectivity improves from 1.59 × 1011 to 9.91 × 1011 Jones, while the external quantum efficiency (EQE) rises from 182% to 1495%. In self-powered mode, the ZnO/MgO/Ag-NIs/NiO device achieves a responsivity of 0.38 mA/W at 365 nm and roughly 203-fold enhancement at 530 nm compared to the Ag-NIs-free device. Furthermore, the optimized device exhibits a fast and stable photoresponse. These findings demonstrate the efficiency of MgO interfacial layers and plasmonic Ag-NIs in improving ZnO/NiO heterostructures for efficient UV–visible broadband self-powered photodetectors.