α -In2Se3-based heterojunction photodetector using Nb-doped MoS2

The built-in electric field at the heterojunction interface can effectively separate electron–hole pairs, which can effectively increase the photocurrent and suppress the dark current. The p–n junction can provide a good depletion layer, so p–n junction photodetectors based on two-dimensional materials are rapidly developing. In this study, Nb-doped MoS2 as a p-type semiconductor and n-type α-In2Se3 were used to form a van der Waals heterojunction photodetector. This photodetector achieves photodetection in the visible to near-infrared range with a responsivity (R) of 87 A/W and a specific detectivity (D*) of 7.5 × 1011 Jones. The carriers introduced by doping make the device less suppressive to dark currents, but maintain a high photoresponsivity. This study adopts doping modulation of the conductive properties for p–n junction photodetectors, and the results are expected to further enhance the photodetection performance.