Tunneling-barrier-controlled sensitive deep ultraviolet photodetectors based on van der Waals heterostructures

Deep ultraviolet (DUV) photodetection usually relies on wide-bandgap semiconductors, which however face challenges in material growth and doping processes. In this work, we proposed and validated a photodetection scheme based on tunneling barrier modulation, achieving highly sensitive DUV photodetection. Using a two-dimensional van der Waals heterostructure, the device integrates MoS2 as the transporting layer for its high carrier mobility and low dark current, few-layered graphene (FLG) as the photon absorption layer, and hexagonal boron nitride (hBN) as the dielectric barrier. The device exhibits an photoresponsivity of 4.4 × 106 A·W-1 and specific detectivity of 1.4 × 1017 cm⋅Hz-1/2⋅W-1 for 250 nm DUV light, with a rejection ratio R250/R450 exceeding 106 for visible light. Unlike conventional photodetectors, the cutoff wavelength is determined by the tunneling barrier rather than the material bandgap. Additionally, this photodetection scheme has been extended to a wide range of materials, utilizing different charge transporting layer (e.g., MoS2, ReS2), barrier layer (e.g., hBN, Al2O3), and photon absorption materials (e.g., FLG, PdSe2, Au, Pd), showcasing its broad adaptability and potential for extensive application. Furthermore, the device has been successfully employed as a power meter for weak UV radiation (0.1 μW·cm-2) and for measuring solar UV irradiance with results matching the meteorological agency's weather reports. Overall, this work introduces an effective approach for developing high-performance DUV photodetectors, highlighting significant potential for applications in the optoelectronic market.