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

Abstract

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.