Vis-NIR photodetector with microsecond response enabled by 2D bismuth/Si(111) heterojunction

Abstract Atomic sheets of bismuth (Bi) have been expected to yield exotic optoelectronic properties, holding great promise for photodetector devices. However, existing Bi thin film photodetectors have limited performance in terms of photoresponsivity or response time, hindering its practical application. Herein, we report an experimental research progress on optoelectronic properties of epitaxial 2D Bi grown on Si(111) substrate. Our 2D Bi/Si(111) heterolayer exhibits inspiring photodetection performance, including a Vis-NIR broadband response with a responsivity up to 80 A W −1 and response time ∼3 μ s, which is attributed to promoted generation and transportation of charge carriers in the heterojunction. 2D Bi/Si(111) here also demonstrates stable and reproducible photo switching behavior. This work paves an avenue to develop photodetectors based on heterointerface between group VA Xene and Si(111) with rapid switching behavior and adequate photoresponsivity.