Enhanced photoresponse of TiO2/MoS2 heterostructure phototransistors by the coupling of interface charge transfer and photogating
MoS2, heterojunction, photodetector, charge injection, photocurrent
Two-dimensional (2D) MoS2 with appealing physical properties is a promising candidate for next-generation electronic and optoelectronic devices, where the ultrathin MoS2 is usually laid on or gated by a dielectric oxide layer. The oxide/MoS2 interfaces widely existing in these devices have significant impacts on the carrier transport of the MoS2 channel by diverse interface interactions. Artificial design of the oxide/MoS2 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 MoS2-based phototransistor with an enhanced photoresponse by interfacing few-layer MoS2 with an ultrathin TiO2 layer. The TiO2 is deposited on MoS2 through the oxidation of an e-beam-evaporated ultrathin Ti layer. Upon a visible-light illumination, the fabricated TiO2/MoS2 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 × 1013 Jones at a zero-gate voltage under a power density of 23.2 μW/mm2. These values are 4.0 and 4.2 times those of the pure MoS2 phototransistor. The significantly enhanced photoresponse of TiO2/MoS2 device can be attributed to both interface charge transfer and photogating effects. Our results not only provide valuable insights into the interactions at TiO2/MoS2 interface, but also may inspire new approach to develop other novel optoelectronic devices based on 2D layered materials.
Tsinghua University Press
Bingxu Liu, Yinghui Sun, Yonghuang Wu, Kai Liu, Huanyu Ye, Fangtao Li, Limeng Zhang, Yong Jiang, Rongming Wang. Enhanced photoresponse of TiO2/MoS2 heterostructure phototransistors by the coupling of interface charge transfer and photogating. Nano Research 2021, 14(4): 982-991.