High-Performance Devices Based on InSe-InGaSe 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-InGaSe van der Waals heterojunctions (vdWHs). The electrical properties of InGaSe alloy samples strongly depend on the ratio of In to Ga, and the InGaSe alloy shows a p-type transport behavior. More importantly, a multilayer InSe-InGaSe vdWH device is demonstrated as a high-performance forward diode, photodiode, and self-powered photodetector (SPPD). The multilayer InSe-InGaSe diode shows a high forward rectification ratio of over 10 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 (*), and responsivity () are 10, 10 Jones, and 49 A W 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.