High-Performance Devices Based on InSe–In_1–xGa_xSe Van der Waals Heterojunctions

Multilayer InSe is a promising material for high-performance optoelectronic applications because of its small direct band gap and good light absorption. However, as a photoconductive photodetector, multilayer InSe photodetectors endure large dark current and high driving power. In this work, we study the electrical properties of InGaSe alloys and demonstrate the high-performance devices based on multilayer InSe–In0.24Ga0.76Se van der Waals heterojunctions (vdWHs). The electrical properties of InGaSe alloy samples strongly depend on the ratio of In to Ga, and the In0.24Ga0.76Se alloy shows a p-type transport behavior. More importantly, a multilayer InSe–In0.24Ga0.76Se vdWH device is demonstrated as a high-performance forward diode, photodiode, and self-powered photodetector (SPPD). The multilayer InSe–In0.24Ga0.76Se diode shows a high forward rectification ratio of over 103 without gate modulation at room temperature, which is superior to most of the multilayer vdWH devices. Moreover, the vdWH photodiode has a broadband photoresponse spectrum (400–1000 nm) and a high-performance photoresponse. The light switching ratio, detectivity (D*), and responsivity (R) are 103, 1012 Jones, and 49 A W–1 for 400 nm illumination, respectively. Furthermore, the vdWH SPPD also shows a sensitive photoresponse to a broadband spectrum of 400–1000 nm. Our work offers an opportunity for multilayer vdWH device applications in high-performance electronic and optoelectronic devices.