Tuning and Probing Interfacial Thermal Conductance between Moiré Superstructures

The operating temperature of emerging two-dimensional (2D) electronic and optoelectronic devices is sensitive to the interfacial thermal conductance of the 2D layered materials. In past work, this thermal transport property has been probed by time-domain thermal reflectance (TDTR) measurements and tuned by electrochemical intercalation. Here we report an experiment that probes interfacial thermal transport between twisted bilayer graphene (TBG) moiré superstructures separated by a thin hexagonal boron nitride layer with the use of steady state resistance thermometry measurements. Besides the thin film platinum gates that can serve as the resistance thermometers, the large temperature coefficient of resistance of TBG enables sensitive measurements of the small temperature drops between the two moiré superstructures. The improved sensitivity allows for the observation of the dependence of the measured interfacial thermal conductance on the gate electric fields applied to the two moiré superstructures. The measurement results are compared to theoretical calculations to understand the field effects on the lattice contribution to the interfacial thermal conductance through the van der Waals interfaces, and to search for an additional contribution due to a predicted Coulombic interaction mechanism.