Self-Driven Gr/WSe<sub>2</sub>/Gr Photodetector with High Performance Based on Asymmetric Schottky van der Waals Contacts
Lei Tong, Can Su, Heng Li, Xinyu Wang, Wenhao Fan, Qingguo Wang, Sándor Kunsági‐Máté, Hui Yan, Shougen Yin
Abstract
Two-dimensional (2D) self-driven photodetectors have a wide range of applications in wearable, imaging, and flexible electronics. However, the preparation of most self-powered photodetectors is still complex and time-consuming. Simultaneously, the constant work function of a metal, numerous defects, and a large Schottky barrier at the 2D/metal interface hinder the transmission and collection of optical carriers, which will suppress the optical responsivity of the device. This paper proposed a self-driven graphene/WSe 2 /graphene (Gr/WSe 2 /Gr) photodetector with asymmetric Schottky van der Waals (vdWs) contacts. The vdWs contacts are formed by transferring Gr as electrodes using the dry-transfer method, obviating the limitations of defects and Fermi-level pinning at the interface of electrodes made by conventional metal deposition methods to a great extent and resulting in superior dynamic response, which leads to a more efficient and faster collection of photogenerated carriers. This work also demonstrates that the significant surface potential difference of Gr electrodes is a crucial factor to ensure their superior performance. The self-driven Gr/WSe 2 /Gr photodetector exhibits an ultrahigh I light / I dark ratio of 10 6 with a responsivity value of 20.31 mA/W and an open-circuit voltage of 0.37 V at zero bias. The photodetector also has ultrafast response speeds of 42.9 and 56.0 μs. This paper provides a feasible way to develop self-driven optoelectronic devices with a simple structure and excellent performance.