Large Scale Graphene/Hexagonal Boron Nitride Heterostructure for Tunable Plasmonics

Vertical integration of hexagonal boron nitride (h‐BN) and graphene for the fabrication of vertical field‐effect transistors or tunneling diodes has stimulated intense interest recently due to the enhanced performance offered by combining an ultrathin dielectric with a semi‐metallic system. Wafer scale fabrication and processing of these heterostructures is needed to make large scale integrated circuitry. In this work, by using remote discharged, radio‐frequency plasma chemical vapor deposition, wafer scale, high quality few layer h‐BN films are successfully grown. By using few layer h‐BN films as top gate dielectric material, the plasmon energy of graphene can be tuned by electrostatic doping. An array of graphene/h‐BN vertically stacked micrometer‐sized disks is fabricated by lithography and transfer techniques, and infrared spectroscopy is used to observe the modes of tunable graphene plasmonic absorption as a function of the repeating (G/h‐BN)_n units in the vertical stack. Interestingly, the plasmonic resonances can be tuned to higher frequencies with increasing layer thickness of the disks, showing that such vertical stacking provides a viable strategy to provide wide window tuning of the plasmons beyond the limitation of the monolayer.