Band Structure Engineering in MoS_2 Based Heterostructures toward High-Performance Phototransistors

摘要

Interfacial band structure engineering paves a promising route to promote the application of 2D semiconductors in optoelectronics, and thereby in the last decades, a great number of studies about heterojunction based on transition-metal dichalcogenides (TMDs) have been implemented. Most of the latest photodetectors mainly consist of a type II band alignment in which, however, the interfacial emission quenching leads to a higher nonradiative rate, an awkward problem for reducing their energy consumption. Here, BaTiO3/MoS2 heterostructures with type I band alignment fabricated by a facile spin-coating method are reported, and their remarkable photodetection performance in comparison with devices based on bare MoS2 (R-lambda: 120 A W-1 vs 1.7 A W-1 and external quantum efficiency (EQE): 4.78 x 10(4)% vs 4.5 x 10(2)% @365 nm) is demonstrated. Optical measurements including micro-Raman and photoluminescence (PL) suggest a carrier extraction process accompanied by the carrier injection occurring in the narrower-bandgap (MoS2) layer, responsible for the increment of carrier population in MoS2 channel and subsequent improvement of detection ability. Hence, the demonstration of such 0D/2D type-I heterostructures through an interfacial control provides valuable information for developing low cost yet superior performance optoelectronic devices in future.