Quantum Hall Transport Measurements of Lateral p-n Junctions Formed via Precise Spatial Photodoping of Graphene/hBN Heterostructures

Heterostructures composed of 2-dimensional (2D) materials are spatially dope in-operando to modify devices for custom functionalities, such as lateral p-n-p junctions. After optically photodoping an hBN/Graphene/hBN heterostructure, detailed magnetotransport measurements including quantum Hall transport show several clear electronic regimes. In the p+-p-p+ and n-n+-n configurations, we see clear quantization of the longitudinal resistance. Using the Landauer-Buttiker model we elucidate the nature of the electrostatic profile at the interface between the doped regions. In the p-n-p configuration, due to the heavily graded junction profile that completely separates the p- and n-Landau level edge states from interacting, an "insulating" state is observed that is not common and has not been measured in previous quantum Hall transport measurements of graphene pnJ devices in high magnetic fields. This insulating state is promising as the basis for a high-performance graphene switching device with a good ON/OFF ratio. In principle, these doping and measurement techniques can be applied to any other 2D heterostructure encapsulated within an hBN sandwich to understand the quality of the electrostatic interface between doped regions.