Plasmon-Acoustic Transducers Based on Graphene–2D Boron Nitride Structures for the Terahertz-Frequency Range

Graphene and 2D hexagonal boron nitride isomorphic to it are promising materials for application in nanoacoustics. Therefore, more detailed study on the possibilities of the development of plasmon-acoustic transducers for nanoacoustics with corresponding numerical estimations of their technical characteristics seems urgent. In this work, the possibility in principle of forming plasmon-acoustic transducers for nanoacoustic devices operating in the terahertz-frequency range is substantiated theoretically and via numerical calculations. A plasmon-acoustic transducer consisting of two subsystems, notably, piezoelectric and plasmon-polariton subsystems, is investigated as the analyzed model. The piezoelectric subsystem is made in the form of a hexagonal boron-nitride nanoribbon—an acoustic duct, the end part of which serves as a piezoelectric transducer exciting elastic waves of the terahertz range. The acoustic duct is overlapped with the plasmon-polariton subsystem in the form of a graphene nanoribbon, in which TM-polarized surface plasmon-polaritons propagate. The introduced electrical impedance of the piezoelectric subsystem and characteristic impedance of the plasmon-polariton subsystem are calculated. It is shown that their values can provide the optimal coordination of a load (the acoustic duct) with the plasmon-polariton waveguide. It is found that graphene nanoplasmonics and nanoacoustics based on piezoelectric planar boron nitride combine well with each other. This opens up broad opportunities for the development of a new class of nanoelectronic devices.