Electrical regulation of interfacial thermal conductance of graphene/MoS2 heterojunction: Uncovering the role of electrons

Abstract

The van der Waals heterojunction of graphene and MoS2 has drawn extensive research in recent years, since it combines the advantages of both materials. The thermal transport across the interface is an important issue in practical application, which has been seldom experimentally studied for graphene/MoS2 heterojunction. Previous work only focused on the phonon coupling without considering the role of interfacial electronics, which caused a deviation between experimental and theoretical results. Herein, we employed photo-thermal Raman technique to characterize the interfacial thermal conductance of graphene/MoS2 heterojunction and revealed a value of 93.2 ± 10.2 MW/m2K on average. This value is much larger than theoretical predictions. Using source-drain bias (VD) and gate voltage in a field effect transistor device, we achieved effect regulation of interfacial electron transport and corresponding thermal conductance in a range of 55.1 ± 5.8 to 304.2 ± 32.1 MW/m2K. At VD with different signs, we uncovered a possible thermal rectification at the interface. We owed the change of interfacial thermal conductance to electron-assisted phonon-coupling, when electron's transfer between graphene and MoS2 may results in the phonon density redistribution.