A self-powered ultraviolet detector based on a single ZnO microwire/p-Si film with double heterojunctions

Abstract

Recently, self-powered devices based on a p–n heterojunction have been widely reported, but there are few reports about self-powered UV detectors based on a single ZnO microwire/p-Si film with double heterojunctions. Compared with the common p–n heterojunction type devices, the fabricated devices with double heterojunctions based on a single n-type ZnO microwire and a p-type Si film exhibited excellent electrical performance such as an ideal rectification behaviour and a low turn-on voltage. At zero bias, the fabricated device can deliver a photocurrent of 71 nA, a high photosensitivity of about 3.17 × 10³ under UV light (0.58 mW cm⁻²) illumination and a fast rising and falling time of both less than 0.3 s. Furthermore, the photocurrent increased with the rising of the optical intensity at low power intensities. The physical mechanism has been explained by energy band diagrams.