Ultralow-Noise Transistors And Photo-Detectors Based On Few-layer ReS₂/Mo-Nolayer MoS₂ Type-? Heterostructures

Heterostructures of transition metal dichalcogenides(TMDs)with type-II band alignment have been studied widely in the field of photovoltaics and photodetection.Here,for the first time,high-performance thin-film transistors and photodetectors based on type-I few-layer ReS2/monolayer(ML)MoS2 heterostructures are demonstrated.Owing to the nature of the type-? heterostructure and the unique properties of few-layer ReS2 and because of specific van der Waals coupling,the fabricated photodetector for ultralow-noise detection shows a leakage current as low as 10-14 A and a noise equivalent power of 6×10-23 W Hz-1/2,which are record values compared to those for similar devices.Calculation results suggest that the incoherent structures of the in-plane anisotropic ReS2 and isotropic MoS2 layers lead to extraordinary changes in the band structure of the heterostructures from an indirect bandgap to a direct one,as the ReS2 layer is changed from an ML to a few-layer one.The experimental results also show that the photocurrent varies with the thickness of the ReS2 layers which can be ascribed to changes in the coupling effect.Heterojunctions formed with 5-6 layers of ReS2 and single layer of MoS2 have the best overall performance.The obtained results strongly suggest that type-I few-layer ReS2/ML TMD heterostructures show great promise for use as extremely low-noise photomultipliers and photodetectors.