Quantum Hall Transport of Spatially-Photodoped Graphene p-n Interfaces

We present our work on spatial photo-doping of an h-BN/Graphene/h-BN heterostructure and characterization of the device by using quantum Hall transport. By optically activating and deactivating the natural defect states in bulk h-BN, which act as remote doping centers for graphene, we change both the carrier density and carrier type in graphene accurately and reversibly by several orders of magnitude. By controlling the position of a spatially resolved light source to activate photo-dopants in selected areas of the sample, lateral doping modulation was achieved and a PNP junction (PNPJ) device was created. In-situ quantum Hall measurements were used to demonstrate the effectiveness of this doping technique and characterize the electrostatic profile of the PNPJ. The Landauer-Buttiker edge-state transport model describes unconventional conduction quantization plateaus experimentally observed when the device is in the P⁺PP⁺ and NN⁺N doping configuration. An “insulating” state appears in the PNP doping regime which is attributed to the heavily graded PN junction profile. This reconfigurable optical doping technique opens many possibilities to engineer novel device concepts and expand the applications of 2D heterostructures.

Son T. Le et al., 2D Mater. 12 015006 (2025).