Enhanced photoresponse of Ti0_(2)/MoS_(2)heterostructure phototransistors by the coupling of interface charge transfer and photogating

Two-dimensional(2D)MoS_(2)with appealing physical properties is a promising candidate for next-generation electronic and optoelectronic devices,where the ultrathin MoS_(2)is usually laid on or gated by a dielectric oxide layer.The oxide/MoS_(2)interfaces widely existing in these devices have significant impacts on the carrier transport of the MoS_(2)channel by diverse interface interactions.Artificial design of the oxide/MoS_(2)interfaces 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 MoS_(2)-based phototransistor with an enhanced photoresponse by interfacing few-layer MoS_(2)with an ultrathin Ti0_(2)layer.The Ti0_(2)is deposited on MoS_(2)through the oxidation of an e-beam-evaporated ultrathin Ti layer.Upon a visible-light illumination,the fabricated Ti0_(2)/MoS_(2)phototransistor exhibits a responsivity of up to 2,199 A/W at a gate voltage of 60 V and a detectivity of up to 1.67×10^(13)Jones at a zero-gate voltage under a power density of 23.2μW/mm^(2).These values are 4.0 and 4.2 times those of the pure MoS_(2)phototransistor.The significantly enhanced photoresponse of Ti0_(2)/MoS_(2)device can be attributed to both interface charge transfer and photogating effects.Our results not only provide valuable insights into the interactions at Ti0_(2)/MoS_(2)interface,but also may inspire new approach to develop other novel optoelectronic devices based on 2D layered materials.