Interfacial Thermal Contact Conductance inside the Graphene-Bi2Te3 Heterostructure

Abstract

Graphene-Bi2Te3, a graphene-based compound with a metal/metalloid heterostructure, is recently discovered to be a potentially novel thermoelectric material, demonstrating unprecedently enhanced thermoelectric efficiencies. The interfacial thermal transport must play an important role in determining the thermoelectric performance of this heterostructure. In particular, the interfacial thermal contact conductance (G(c)) must be known in order to correctly elaborate the thermoelectric performances of graphene-Bi2Te3. Furthermore, the large nonlinear optoelectric response of this heterostructure redefines both the graphene thermal conductivity (k(g)) and its optical absorbance (A(g)). A significantly suppressed A(g) is predicted as low as 0.86% from its nominal value of 2.72% when suspended, from the transfer matrix calculations based on the Fresnel principle. Both G(c) and k(g) are simultaneously determined from the optothermal Raman thermometry by duplexing the Raman data sets using two different objective magnifications (20x and 100x), which allows for the matching of the number of unknowns (G(c) and k(g)) with the corresponding two Raman data sets. The thermal properties of G(c) and k(g) for the graphene-Bi2Te3 heterostructure are first determined as 3.455 +/- 0.619 x 10(6) W m(-2) K-1 and 440.124 +/- 76.265 W m(-1) K-1, respectively.