Ultrahigh Photoresponsivity Enabled by Carrier Multiplication in a Self-Powered Solar-Blind Photodetector Based on the WS<sub>2</sub>/Graphene Heterostructure
Rongjian Ma, Hang Ren, Chuxin Yan, Yuanzheng Li, Jixiu Li, Wei Xin, Weizhen Liu, Xingang Zhao, Lin Yang, Shengnan Feng, Haiyang Xu, Yichun Liu, Xinfeng Liu
Abstract
The development of high-performance, low-power solar-blind photodetectors (SBPDs) holds significant promise for both military and civilian applications. Compared with wide-bandgap semiconductors, two-dimensional (2D) materials exhibit advantageous characteristics in the threshold and efficiency of carrier multiplication (CM) due to enhanced Coulomb interaction and relaxed momentum conservation. This allows one incident high-energy photon to generate two or more electron–hole pairs effectively, positioning them as viable alternatives for the fabrication of high-performance self-powered SBPDs. Here, we have designed a vertically aligned 2D WS 2 /graphene photodetector with Au as the contact electrodes, forming a unilateral Schottky junction to facilitate the efficient transfer of high-energy electrons generated in the WS 2 to the graphene without thermal relaxation. This enables efficient CM within graphene, resulting in an ultrahigh responsivity of 77 mA/W and an external quantum efficiency of 36% at 265 nm light with zero bias. This work offers invaluable insights into the development of next-generation SBPDs with high performance and low power consumption.