Doping Engineering in the MoS 2 /SnSe 2 Heterostructure toward High-Rejection-Ratio Solar-Blind UV Photodetection.

The intentionally designed band alignment of heterostructures and doping engineering are keys to implement device structure design and device performance optimization. According to the theoretical prediction of several typical materials among the transition metal dichalcogenides (TMDs) and group-IV metal chalcogenides, MoS 2 and SnSe 2 present the largest staggered band offset. The large band offset is conducive to the separation of photogenerated carriers, thus MoS 2 /SnSe 2 is a theoretically ideal candidate for fabricating photodetector, which is also verified in the experiment. Furthermore, in order to extend the photoresponse spectrum to solar-blind ultraviolet (SBUV), doping engineering is adopted to form an additional electron state, which provides an extra carrier transition channel. In this work, pure MoS 2 /SnSe 2 and doped MoS 2 /SnSe 2 heterostructures are both fabricated. In terms of the photoelectric performance evaluation, the rejection ratio R 254 /R 532 of the photodetector based on doped MoS 2 /SnSe 2 is five orders of magnitude higher than that of pure MoS 2 /SnSe 2 , while the response time is obviously optimized by 3 orders. The results demonstrate that the combination of band alignment and doping engineering provides a new pathway for constructing SBUV photodetectors.