Band Structure Engineering in MoS2 Based Heterostructures toward High‐Performance Phototransistors

Abstract 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, BaTiO 3 /MoS 2 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 MoS 2 ( R λ : 120 A W −1 vs 1.7 A W −1 and external quantum efficiency (EQE): 4.78 × 10 4 % vs 4.5 × 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 (MoS 2 ) layer, responsible for the increment of carrier population in MoS 2 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.