Thermoelectric amplification of phonons in graphene

Abstract

Amplification of acoustic phonons due to an external temperature gredient (∇T ) in Graphene was studied theoretically. The threshold temperature gradient (∇T ) g 0 at which absorption switches over to amplification in Graphene was evaluated at various frequencies (ω q ) and temperatures (T ).

The Influece of The Laser on Acoustic Phonon Amplification in Parabolic Potential Well

“…A laser field irradiates which is normal to the x-y plane, its polarization is along the x axis, and its strength is expressed as a vector potential ( ) A t  . The Hamiltonian for the system of the electrons and phonons in the case of the presence of the laser field is written as [4]:…”

“…The development of methods for the generation and amplification of coherent acoustic phonons in low-dimensional structures [1][2][3][4][5][6]. The main results of these papers are that by absorption of laser field energy, the interaction of the laser field with electron can lead to the excitation of higher harmonics and the amplification of phonon.…”

Acoustoelectric current in graphene due to electron deformation potential and piezoelectric phonon couplings

“…When a SAW propagates in graphene, an AE current (I AE ) flows between two attached electrodes, as shown in figure 1(a). From the existing experimental and theoretical studies exploring the interaction of charge carriers with sound in MLG, it turns out that it is still difficult to completely understand the dynamic properties of AE effects including the I , AE as it is influenced by a large number of parameters which includes the properties of graphene [18], intensity and frequency of the SAW [23,[26][27][28][29][30][31][32][33][34][35][36][37][38][39], temperature [28], time [30], carrier concentration [23,35], doping [30], magnitude and sign of bias voltage (Vbias) [28,32,35], illumination [26], substrate, as well as the type of piezoelectric crystal and the interface between the graphene and the piezoelectric crystal surface [31,32,36]. The ratio of the difference between the complete and approximate Fermi-Dirac functions at k 1 THz and 2 10 m .…”

“…We present a theoretical investigation on the AE current I AE ( ) generated by acoustic phonons interacting with electrons through piezoelectric (PE) and deformation potential (DP) electron phonon coupling in a MLG using the Boltzmann transport equation (BTE) approach. In a few theoretical studies, the investigations on attenuation/absorption coefficient/rate and acoustoelectric current in the BTE approach have been reported [36][37][38][39]. The results have been obtained in the hyper sound regime where  ql 1.…”