Influence of external temperature gradient on acoustoelectric current in graphene

Abstract

Recent analyses of thermoelectric amplification of acoustic phonons in Free-Standing Graphene (FSG) ${\Gamma }_q^{grap}$ have prompted the theoretical study of the influence of external temperature gradient ($\nabla T$) on the acoustoelectric current $j_T^{(grap)}$ in FSG. Here, we calculated thermal field on open circuit ($j_T^{(grap)}=0$) to be $(\nabla T{)}^g=746.8K{m}^{-1}$. We then calculated acoustoelectric current ($j_T^{(grap)}$)to be $1.1mA\mu m^{-2}$ for $\nabla T=750.0K{m}^{-1}$, which is comparable to that obtained in semiconductors ($1.0mA\mu m^{-2}$), the thermal-voltage $(V_T{)}_0^g$ to be $6.6\mu V$ and the Seebeck coefficient $S$ as $8.8\mu V/K$. Graphs of the normalized $j_T^{(grap)}/j_0$ versus ${\omega }_q$, $T$ and $\nabla T/T$ were sketched. For $j_T^{(grap)}$ on $T$ for varying ${\omega }_q$, Negative Difference Conductivity (NDC) ($|\frac{\partial j}{\partial T}|<0$) was observed in the material. This indicates graphene is a suitable material for developing thermal amplifiers and logic gates.

14 pages, 7 pages