Comparison of thermal conductance of graphene/SiO2 and graphene/Au interfaces based on Raman optothermal method

Abstract

Due to the atom-scale thickness and the large surface area to volume ratio, the interfacial thermal conductance between graphene (Gr) and substrates is a critical property for thermal management application of graphene into micro/nano scale electronic devices. It has been widely proved to be dependent on the interfacial phonons transport, material morphology, and interfacial force. The material category of the substrate is related to the interfacial thermal conductance, but, the experimental studies of which are lacking. In this work, the thermal conductance (G) of Gr on SiO2 and Au substrates is measured using Raman optothermal approach combined with finite element simulations. GGr/SiO2 is determined to be ×103 W · m−2 · K−1, while GGr/Au is (1.7 ± 0.2) × 104 W · m−2 · K−1. They are in the same order of magnitude, but GGr/Au is a little larger than twice of GGr/SiO2. Compared with the elastic-phonon-scattering-dominated heat transfer across the Gr/SiO2 interface, the interfacial thermal conductance of Gr/Au is enhanced by the increased probability of multi-phonons inelastic scatterings due to the lower Debye temperature of Au than the ambient temperature and the additional contribution from electron scatterings. Besides, the interfacial adhesion energy of Gr/Au is higher than that of Gr/SiO2 which contributes to GGr/Au larger than GGr/SiO2. The metallic substrate like Au will benefit the heat transfer across graphene interfaces, with respect to the nonmetallic substrate like SiO2. Our results offer new insights into the interfacial heat transfer mechanisms between graphene and nonmetallic (or metallic) substrates. They also provide guidance for tuning the interfacial heat transfer in applications of 2D materials in thermal management of compact devices by switching the material category of substrates.