Thermoelectric amplification of phonons in graphene

Abstract

Amplification of acoustic in-plane phonons due to an external temperature gradient (rT) in single-layer graphene (SLG) was studied theoretically. The threshold temperature gradient ðrTÞ g 0 and the threshold voltage ðVTÞ g 0 in SLG were evaluated. For T ¼ 77 K, the calculated value fo ðrTÞ ¼ 746:8 K=cm and ðVTÞ ¼ 6:6 mV. The calculation was done in the hypersound regime. Further, the dependence of the normalized amplification ðC=C0Þ on the frequency xq and rT=T were evaluated numerically and presented graphically. The calculated threshold temperaturegradient ðVTÞ g 0 for SLG was higher than that obtained for homogeneous semiconductors ( n-InSb) ðrTÞ hom 103 K=cm, superlattices ðrTÞ SL 0384 K=cm, and cylindrical quantum wire ðrTÞ cqw 102 K=cm. This makes SLG a much better material for thermoelectric phonon