A Self-Powered Photovoltaic Photodetector Based on a Lateral WSe<sub>2</sub>-WSe<sub>2</sub> Homojunction
Chaoyang Tan, Huanhuan Wang, Xiangde Zhu, Wenshuai Gao, Hui Li, Jiawang Chen, Gang Li, Lijie Chen, Junmin Xu, Xiaozong Hu, Liang Li, Tianyou Zhai
Abstract
Lateral homojunctions made of two-dimensional (2D) layered materials are promising for optoelectronic and electronic applications. Here, we report the lateral WSe2-WSe2 homojunction photodiodes formed spontaneously by thickness modulation in which there are unique band structures of a unilateral depletion region. The electrically tunable junctions can be switched from n–n to p–p diodes, and the corresponding rectification ratio increases from about 1 to 1.2 × 104. In addition, an obvious photovoltaic behavior is observed at zero gate voltage, which exhibits a large open voltage of 0.49 V and a short-circuit current of 0.125 nA under visible light irradiation. In addition, due to the unilateral depletion region, the diode can achieve a high detectivity of 4.4 × 1010 Jones and a fast photoresponse speed of 0.18 ms at Vg = 0 and Vds = 0. The studies not only demonstrated the great potential of the lateral homojunction photodiodes for a self-power photodetector but also allowed for the development of other functional devices, such as a nonvolatile programmable diode for logic rectifiers.