Ultralow Dark Current Room-Temperature Infrared Photodetector Based on InSb Nanosheets/MoS₂ Van der Waals Heterostructure

As a narrow-bandgap semiconductor, InSb is widely used in infrared (IR) detection due to its excellent performance and other characteristics such as ultrahigh electron mobility, extremely high quantum efficiency, and robust chemical properties. Herein, an ultralow dark current room-temperature IR photodetector based on InSb nanosheets (NSs)/MoS₂ flakes van der Waals (vdW) heterostructure is presented. Benefiting from a large surface-to-volume ratio and phonon scattering suppressed on the nanostructure, InSb NSs devices have high photosensitivity and low dark current density (16.67 A cm⁻²). To further suppress the dark current, a vdW heterojunction composed of InSb NSs and MoS₂ is fabricated. When the InSb NSs/MoS₂ vdW heterostructures’ photodetector work on a photovoltaic model (zero-bias operation), the device shows a dark current density as low as 0.12 A cm⁻² at room temperature, exhibiting a high external quantum efficiency (EQE) of 3.6 × 10²%, the responsivity of 3.8 A W⁻¹, and detectivity of 1.2 × 10⁹ cm Hz^1/2 W⁻¹ under 1310 nm laser illumination. These results demonstrate that InSb NSs vdW heterostructure is a feasible scheme to realize InSb room-temperature IR detection.