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

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 (Rλ: 120 A W−1 vs 1.7 A W−1 and external quantum efficiency (EQE): 4.78 × 104% vs 4.5 × 102% @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. An improved photodetector based on BaTiO3/MoS2 heterostructures with type I band alignment is demonstrated compared to bare MoS2 (Rλ: 120 vs 1.7 A W−1; external quantum efficiency (EQE): 4.78 × 104% vs 4.5 × 102% @365 nm). Optical measurements suggest that a carrier extraction process accompanied by carrier injection occurs in the MoS2 layer, leading to the increasing carrier population in channel.