Enhanced photoresponse of Ti02/MoS2heterostructure phototransistors by the coupling of interface charge transfer and photogating

Two-dimensional(2D)MoS₂with appealing physical properties is a promising candidate for next-generation electronic and optoelectronic devices,where the ultrathin MoS₂is usually laid on or gated by a dielectric oxide layer.The oxide/MoS₂interfaces widely existing in these devices have significant impacts on the carrier transport of the MoS₂channel by diverse interface interactions.Artificial design of the oxide/MoS₂interfaces would provide an effective way to break through the performance limit of the 2D devices but has yet been well explored.Here,we report a high-performance MoS₂-based phototransistor with an enhanced photoresponse by interfacing few-layer MoS₂with an ultrathin Ti0₂layer.The Ti0₂is deposited on MoS₂through the oxidation of an e-beam-evaporated ultrathin Ti layer.Upon a visible-light illumination,the fabricated Ti0₂/MoS₂phototransistor exhibits a responsivity of up to 2,199 A/W at a gate voltage of 60 V and a detectivity of up to 1.67×10¹³Jones at a zero-gate voltage under a power density of 23.2μW/mm².These values are 4.0 and 4.2 times those of the pure MoS₂phototransistor.The significantly enhanced photoresponse of Ti0₂/MoS₂device can be attributed to both interface charge transfer and photogating effects.Our results not only provide valuable insights into the interactions at Ti0₂/MoS₂interface,but also may inspire new approach to develop other novel optoelectronic devices based on 2D layered materials.