Defect-Assisted Photocurrent Generated in Landau-Quantized Graphene/Carbon-Doped h-BN/Graphite van der Waals Tunnel Junctions

Carbon-related defects in carbon-doped hexagonal boron nitride (h-BN:C) have emerged as an ideal material for probing the local electric properties of two-dimensional (2D) materials via defect-assisted tunneling. This study demonstrates the generation of defect-assisted photocurrent in a Landau-quantized monolayer graphene (MLG)/h-BN:C/graphite van der Waals tunnel junction. The photoresponse of the junction was investigated under the cyclotron resonance of MLG, where the energy of the light irradiation coincided with the inter-Landau level (LL) optical transition. We demonstrate photocurrent generation under a specific gate and interlayer bias to satisfy the following conditions: 1) The Fermi energy (EF) of the MLG is located at the boundary between the quantum Hall states (QHS) and non-QHS. 2) The energy of the LLs below EF of the MLG coincides with that of the carbon defect in the h-BN barrier. These findings contribute to the development of mid-infrared photodetection and local sensing of cyclotron resonance using defect-assisted tunneling.