Low power photodetector based on graphene-WS2-Au structure

Abstract

At present, photodetectors based on traditional semiconductor materials no longer meet the needs of the rapid development of science and technology. Two-dimensional materials have attracted wide attention in academia and industry because of their excellent electrical and optical properties. In addition, WS2 is considered a promising photodetector material because of its tunable band structure, high stability, and high carrier mobility. In this paper, a metal-semiconductor-metal photodetector based on mechanically stripped WS2 material is designed, with a metal used as electrode material. However, the Schottky barrier and trap state between metal-semiconductor structures will lead to decreasing carrier collection efficiency. To further improve the performance of the detector, we consider graphene as the electrode material and design a photodetector with Au–WS2–Graphene (Gra)–Au structure. According to experiments, using graphene as an electrode can significantly improve the photocurrent gain and reduce the dark current. At 1 V positive bias and 3.9 nW illumination power, the responsivity of the Au–WS2–Gra–Au structure is as high as 29.0 A/W, which indicates that it has excellent ability in light response and weak light detection. This research makes it possible to realize photodetectors with low power consumption and ultra-high light responsiveness, which have great application prospects in practical electronic devices.