Infrared Proximity Sensors Based on Photo‐Induced Tunneling in van der Waals Integration
Young Rae Kim, Thanh Luan Phan, Kye Whan Cho, Won Tae Kang, Kunnyun Kim, Young Hee Lee, Woo Jong Yu
Abstract
Abstract Infrared (IR) detectors based on photo‐induced tunneling in van der Waals heterostructures (vdWHs) of graphene/h‐BN/graphene or MoS 2 /h‐BN/graphene exhibit extremely low dark currents owing to a large electron barrier. However, a lack of tunneling barrier materials except for h‐BN for 2D vdWHs limits their further enhancement. In this study, a broadband detection is reported with high sensitivity and fast photoresponse of IR proximity sensor by a vdW integration (2D‐3D) of graphene or MoS 2 , with NiO/Ni as the IR absorber and hole selective transport layer/counter electrode. The low Schottky barrier height of the reported junctions suppresses dark current with a high detectivity ≈ 10 14 Jones and generates a photocurrent by transporting photo‐excited carriers through a low hole barrier at a wide wavelength. Two types of integrated IR proximity sensor applications are developed: a passive sensor (MoS 2 /NiO/Ni) for the near‐IR (NIR) range and an active sensor (Gr/NiO/Ni) for the mid‐IR (MIR) range. The former shows a broadband photoresponse to reflect the NIR, while the latter absorbs human body irradiation (2–16 µm wavelength) with a fast photoresponse of 3.5 s (rise time) and 1.8 s (fall time). The fabricated sensors utilize low power, broadband detection, high sensitivity, fast photoresponse, and large‐scale area at room temperature.