Multiheterojunction Photodetectors Based on Type-II CdSe-CdTe-ZnTe Heterojunctions: Structural Design and Optimization for an Enhanced Transient Response under UV–Vis–NIR Light

Abstract

Ingenious microstructure design and a suitable multicomponent strategy are still challenging for improving the photodetector performance. In this paper, vertically arranged CdSe-CdTe-ZnTe core–shell nanowire arrays with one-dimensional (1D) bivalve structures have been successfully synthesized by the vapor–liquid–solid growth method assisted by gold catalysts. The core–double-shell nanowires have an average length of 5 μm and a diameter of 10 nm and have been applied in the production of ultraviolet–visible (UV–vis)–NIR photodetectors. Owing to the cascade band edges and the enhanced charge separation, the rate of charge recombination is greatly reduced. In addition, the spatially indirect interband transition of photogenerated carriers breaks the limit of photon energy absorption of the single-component material, thus further extending the detection range to near-infrared light and effectively accelerating the transient response of the photodetector from 3.8 to 0.1 s compared to that based on the CdSe-CdTe single-shell structure. This work proves that the one-dimensional core–double-shell structure can effectively improve the transient response of the photodetector while still maintaining the piezo-phototronic effect-enhanced performance of the core–shell nanowire array.