Near-Infrared Photodetectors Based on MoTe₂/Graphene Heterostructure with High Responsivity and Flexibility

Abstract

2D transition metal dichalcogenides (TMDCs) have attracted considerable attention due to their impressively high performance in optoelectronic devices. However, efficient infrared (IR) photodetection has been significantly hampered because the absorption wavelength range of most TMDCs lies in the visible spectrum. In this regard, semiconducting 2D MoTe₂ can be an alternative choice owing to its smaller band gap ≈1 eV from bulk to monolayer and high carrier mobility. Here, a MoTe₂ /graphene heterostructure photodetector is demonstrated for efficient near-infrared (NIR) light detection. The devices achieve a high responsivity of ≈970.82 A W^-1 (at 1064 nm) and broadband photodetection (visible-1064 nm). Because of the effective photogating effect induced by electrons trapped in the localized states of MoTe₂ , the devices demonstrate an extremely high photoconductive gain of 4.69 × 10⁸ and detectivity of 1.55 × 10¹¹ cm Hz^1/2 W^-1 . Moreover, flexible devices based on the MoTe₂ /graphene heterostructure on flexible substrate also retains a good photodetection ability after thousands of times bending test (1.2% tensile strain), with a high responsivity of ≈60 A W^-1 at 1064 nm at V_DS = 1 V, which provides a promising platform for highly efficient, flexible, and low cost broadband NIR photodetectors.