Diffusive Thermoelectric Power in Highly Asymmetric Bilayer Graphene Nanoribbons

Abstract

We present a simplified theoretical analysis of diffusive thermoelectric power (TEP) in a highly asymmetric bilayer graphene nanoribbon (BGN) within the framework of the tight binding formalism. BGN possesses two sets of subbands, the upper and the lower. We have shown that, for a highly asymmetric BGN (D = c, where D and c are the gap and interlayer coupling constant, respectively), the density of states in the lower set of subbands increases compared with the upper. The effect of ribbon width on the TEP under the aforementioned phonon scattering regime has also been quantitatively shown. The TEP exhibits an oscillatory dependence on ribbon width. Reflection coefficients of the carriers in both the upper and lower subbands have been treated in detail. Results of the ballistic formalism have been obtained as a special case in the present analyses under certain limiting conditions, forming an indirect validation of our theoretical formulations.