Ultrasensitive WSe2/MoSe2 heterojunction photodetector enhanced by photogating effect

Abstract

Two-dimensional (2D) materials have attracted an increasing attention in state-of-the-art optical sensing applications. However, the performance of photodetectors based on 2D materials are limited by weak light absorption, resulting in a low optical response. In this work, a highly sensitive and fast photodetector is fabricated based on WSe2/MoSe2 vertical p-n van der Waals heterojunction via an effective photogating effect. Benefiting from the good energy band alignment and photogating effect, a fast separation of photogenerated carriers and high optical gain are obtained. As a result, the photodetector exhibits a high responsivity of 1260 A/W, a specific detectivity of 6.05 × 1012 Jones, a large external quantum efficiency approaching 2.68 × 105%, and a short response time of 3.5 ms. This work provided a facile strategy for improving the device performance to meeting the increasing demand of highly sensitive light sensing devices.