Interfacial engineering and heterostructures designing are two efficient routes to improve photoelectric characteristics of a photodetector. Herein, a Ti3 C2 MXene/Si heterojunction photodetector with ultrahigh specific detectivity (2.03 × 1013 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 SiOx layer and the control of Ti3 C2 MXene thickness to suppress the dark noise current and improve the photoresponse. The photodetector demonstrates a high light on/off ratio of over 106 , 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 Ti3 C2 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.
Keywords: MXene; Ti 3C 2; photodetector; self-powered; van der Waals heterojunction.
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