Substrate-independent thermal conductance of Al/graphene/dielectric interfaces from 80 to 300 K

Despite the importance of physical understanding of interfacial thermal conductance (G) for metal/graphene (Gr)/dielectric interfaces, there exists a large discrepancy regarding the role of dielectric substrates in thermal transport across graphene interfaces in previous studies. In this work, we experimentally investigate the impact of dielectric substrates on thermal transport across metal/Gr/dielectric interfaces through accurately measuring G for various Al/Gr/dielectric interfaces over a temperature range of 80–300 K, using both standard time-domain thermoreflectance (TDTR) and differential TDTR. We find that G of Al/Gr/dielectric falls within the range of 29–36 MW m−2 K−1 at room temperature and displays notably weak substrate dependence even with the dielectric Debye temperature ranging from 500 to 1050 K. This substrate independence is attributed to the dominant role of phonon transmission at metal/Gr interfaces in thermal transport across metal/Gr/dielectric interfaces, and the insignificant impacts of phonon density of states overlap on G for Gr/dielectric interfaces. Moreover, through the comparison of our measured G for both Gr/crystalline-Al2O3 and Gr/amorphous-Al2O3, we demonstrate that contrary to previous predictions, the crystalline and amorphous forms of dielectrics do not play a substantial role in thermal transport across graphene interfaces. Our work fills the gap in experimental data on G for metal/Gr/dielectric interfaces and provides valuable insights into physical understanding of thermal transport mechanisms across such interfaces.