In-situ fabrication of PtSe2/MoS2 van der Waals heterojunction for self-powered and broadband photodetector

Two-dimensional transition metal dichalcogenides (2DTMDs) and their van der Waals heterojunctions (vdWHs) have garnered significant attention working as the channel material of optoelectronics. The development of new heterojunction growth schemes may also provide better performance for optoelectronic devices. In this paper, PtSe2 thin films with controllable size and thickness are directly grown on MoS2 nanosheet by sputteringselenization two-step growth method. The photodetector with PtSe2/MoS2 heterojunction exhibits a type-I band alignment and leads to an impressive broadband spectral photoresponse (405 to 1550 nm). It can achieve responsivity as high as 5.42 A/W, a detectivity of 2.52 x 1010 Jones, and a fast response rate (92/112 mu s for rise/fall time respectively). In addition, the device has excellent stability in the air atmosphere and keeps its photoresponse after even six months. The in-situ growth method provides a new scheme to construct heterojunctions of 2DTMDs and develop energy-efficient photodetectors with enhanced performance. It also supplements the practical production and application of large-scale broadband detectors.