Two-dimensional α-In₂Se₃-based ferroelectric semiconductor junction for reconfigurable photodetectors

The proliferation of visual information promoted in part by the Internet of Things is increasing demand for high-quality imaging, which in turn imposes more stringent physical requirements on photodetectors. Given that dark current is a significant figure of merit for photodetectors, we report herein a vertical ferroelectric semiconductor junction based on two-dimensional α-In₂Se₃ that suppresses the dark current and, thereby, enhances photodetection sensitivity. By utilizing the tight coupling between the ferroelectric and semiconductor properties of α-In₂Se₃, the two-terminal graphene-ferroelectric semiconductor-graphene crossbar structure demonstrates typical memristive behavior. The conductance, reflecting the dark current, is effectively regulated by modulating the height of the out-of-plane ferroelectric polarization-induced Schottky barrier height modulation between α-In₂Se₃ and graphene. As a result, the dark current is suppressed to 14 nA when α-In₂Se₃ is polarized down, which is a 50-fold decrease from 660 nA of dark current when α-In₂Se₃ is polarized up. Furthermore, α-In₂Se₃ exhibits excellent optoelectronic properties, demonstrating a high responsivity of 4.3 × 10⁴ A/W, a fast response speed of 43 μs, and a broadband response spectrum from the visible to 980 nm. The combination of semiconductor and ferroelectric properties means that such devices may be used in self-powered, broadband, and highly integrated optoelectronic platforms.