A self-driven photodetector based on a SnS<sub>2</sub>/WS<sub>2</sub> van der Waals heterojunction with an Al<sub>2</sub>O<sub>3</sub> capping layer
Hsiang-Chun Wang, Yuheng Lin, Xiao Liu, Xuanhua Deng, Jianwei Ben, Wenjie Yu, Deliang Zhu, Xinke Liu
Abstract
Photodetectors based on two-dimensional (2D) materials have attracted considerable attention because of their unique properties. To further improve the performance of self-driven photodetectors based on van der Waals heterojunctions, a conductive band minimum (CBM) matched self-driven SnS 2 /WS 2 van der Waals heterojunction photodetector based on a SiO 2 /Si substrate has been designed. The device exhibits a positive current at zero voltage under 365 nm laser illumination. This is attributed to the built-in electric field at the interface of the SnS 2 and WS 2 layer, which will separate and transport the photogenerated carriers, even at zero bias voltage. In addition, the Al 2 O 3 layer is covered by the surface of the SnS 2 /WS 2 photodetector to further improve the performance, because the Al 2 O 3 layer will introduce tensile stress on the surface of the 2D materials leading to a higher electron concentration and smaller effective mass of electrons in the films. This work provides an idea for the research of self-driven photodetectors based on a van der Waals heterogeneous junction.