2D WS₂ Based Asymmetric Schottky Photodetector with High Performance

Abstract

Abstract Two‐dimensional‐material‐based self‐driven photodetectors show high sensitivity, fast and broadband response under built‐in electric field in a P–N junction configuration. However, the methods, including doping and multiple transfer processes, for constructing the heterostructures is complex and time‐costing. On the other hand, asymmetric Schottky barrier heights caused by metal electrodes scale, kinds, contact area and thickness can lead to zero‐bias driven photo‐response. In this work, a metal–semiconductor–metal irregular WS 2 photodetector with symmetric electrodes are achieved by wet‐transfer. A high zero‐bias photo‐responsivity of 777 mA W −1 , a fast response speed of 7.8/37.2 ms, a I light / I dark ratio of 10 4 and a high detectivity of 4.94 × 10 11 Jones under 405 nm light are obtained because of a Schottky barrier height difference of ≈50.2 mV through Fermi‐level pinning effect and different contact area. The responsivity at −2 V is stable in the range of 2.23 to 3.45 A W −1 and the empirical factor reaches to 0.99 by the efficient carrier generation process. The WS 2 asymmetric Schottky photodetectors outperform most heterostructure based photodiodes. This paper provides a facile route toward self‐powered photodetectors with high performance, easy processing and simple architecture for future applications.