Quantifying thermal boundary conductance of 2D-3D interfaces

Heat dissipation in next-generation electronics based on two-dimensional (2D) materials is a critical issue in their development and implementation. A bottleneck for heat removal from the 2D layer into its supporting substrate is the thermal boundary conductance (TBC) of the 2D-3D interface, which is impacted by their structure and composition. Here we investigate the temperature-dependent TBC of 42 interfaces formed between a group of six 2D materials and seven crystalline and amorphous substrates. Our results show that the TBC can be varied by nearly two orders of magnitude, from 0.6 MW.m−2.K−1 (h-BN on diamond) to 40 MW.m−2.K−1 (h-BN on SiO2), for the same 2D layer by changing the substrate material. We find that amorphous materials boost the TBC due to the low-frequency Boson peak feature in their vibrational density of states (vDOS) relative to their crystalline counterparts, whose vDOS follows a Debye model at low frequency, assuming the two interfaces have the same adhesion. For crystalline substrates, we correlate constituent material properties with the calculated TBCs and find that TBC depends on a combination of the speed of sound, Debye temperature, density of the substrate, and bandwidth of the flexural branch in the 2D material.