Thermal transport across solid-solid interfaces enhanced by pre-interface isotope-phonon scattering

Abstract

Thermal transport across solid interfaces can play critical roles in the thermal management of electronics. In this letter, we use non-equilibrium molecular dynamics simulations to investigate the isotope effect on the thermal transport across SiC/GaN interfaces. It is found that engineered isotopes (e.g., 10% 15N or 71Ga) in the GaN layer can increase the interfacial thermal conductance compared to the isotopically pure case by as much as 23%. Different isotope doping features, such as the isotope concentration, skin depth of the isotope region, and its distance from the interface, are investigated, and all of them lead to increases in thermal conductance. Studies of spectral temperatures of phonon modes indicate that interfacial thermal transport due to low-frequency phonons (< 20 THz) is enhanced after isotopes are introduced. These results suggest that the enhanced thermal conductance is related to the isotope-phonon scattering, which facilitates the redistribution of phonon energy among different modes to favor a better overall interfacial thermal transport. This work may provide insights into interfacial thermal transport and useful guidance to practical material design.