Interface Engineering Ti3C2 MXene/Silicon Self‐Powered Photodetectors with High Responsivity and Detectivity for Weak Light Applications

Abstract Interfacial engineering and heterostructures designing are two efficient routes to improve photoelectric characteristics of a photodetector. Herein, a Ti 3 C 2 MXene/Si heterojunction photodetector with ultrahigh specific detectivity (2.03 × 10 13 Jones) and remarkable responsivity (402 mA W −1 ) at zero external bias without decline as with increasing the light power is reported. This is achieved by chemically regrown interfacial SiO x layer and the control of Ti 3 C 2 MXene thickness to suppress the dark noise current and improve the photoresponse. The photodetector demonstrates a high light on/off ratio of over 10 6 , an outstanding peak external quantum efficiency ( EQE ) of 60.3%, while it maintains an ultralow dark current at 0 V bias. Moreover, the device holds high performance with EQE of over 55% even after encapsulated with silicone, trying to resolve the air stability issue of Ti 3 C 2 MXene. Such a photodetector with high detectivity, high responsivity, and self‐powered capability is particularly applicable to detect weak light signal, which presents high potential for imaging, communication and sensing applications.