Abstract
The amplification of surface acoustic waves (SAWs) by a multilayer graphene (MLG)-based amplifier is studied. The conductivity of massless carriers (electrons or holes) in graphene in an external drift electric field is calculated using Boltzmann’s equation. At some carrier drift velocities, the real part of the variable conductivity becomes negative and MLG can be employed in SAW amplifiers. Amplification of Blustein’s and Rayleigh’s SAWs in CdS, a piezoelectric hexagonal crystal of the symmetry group C6v, is considered. The corresponding equations for SAW propagation in the device are derived and can be applied to other substrate crystals of the same symmetry. The results of the paper indicate that MLG can be considered as a perspective material for SAW amplification and related applications.
Highlights
The interaction between acoustic waves and carrier currents is one of the central problem in applied physics
II, when the real part of the variable conductivity becomes negative, perturbations due to an external electric field can be amplified by the graphene carrier current, for example, if the graphene sheets are placed on a piezoelectric crystal
We studied the conductivity of a graphene charge carrier plasma in the presence of external longitudinal electric fields and the amplification of surface acoustic wave (SAW) in a piezoelectric crystal using multilayer graphene (MLG) structures
Summary
The interaction between acoustic waves and carrier currents is one of the central problem in applied physics. Owing to the form of the spectrum, there are many features defining the charge transport,[7,8] in particular, the high-current transport.[9,10,11] A series of related studies was performed recently to understand (i) the conductivity of graphene and its carrier dynamics,[12,13,14,15,16,17] (ii) plasmonic effects,[18,19,20,21] (iii) the own phonon generation by the carrier current,[22,23,24,25] (iv) the interaction between graphene electrons and SAWs,[26,27,28,29] and (v) sandwich-like “graphene-piezoelectric” structures, which allow one to create a new class of opto-acousto-electronic devices.[30,31,32,33,34] the problem of modeling SAW amplification in graphene-based SAW amplifiers has not been studied systematically to date. We discuss the advantages of MLG structures for the applications
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