Molecular Dynamics Study of Thermal Transport across Diamond/Cubic Boron Nitride Interfaces

Abstract The thermal transport properties at the interface of diamond and cubic boron nitride (c-BN) heterostructures significantly influence heat dissipation in high-power electronic and optoelectronic devices. However, a fundamental understanding of the various parameters modulating the interfacial thermal conductance is still lacking. In this work, we employ non-equilibrium molecular dynamics (NEMD) simulations to systematically investigate the effects of system size, temperature, and defect density on the interfacial thermal conductance across diamond/c-BN interfaces. The results indicate a positive correlation between system length and interface thermal conductance when below the phonon mean free path threshold, attributable to ballistic phonon transport regimes in smaller domains. Additionally, we observe an incremental enhancement in interface thermal conductance with increasing temperature, stemmed from intensified phonon-phonon interactions and reduced boundary scattering of thermal energy carriers. The introduction of vacancy and twinning defects is found to hinder interfacial thermal transport due to heightened phonon scattering processes that impede phononic transmission. The interatomic interactions and lattice dynamics are analyzed to provide insights into the underlying thermal transport physics at the atomistic scale. By tuning the system length from 4 to 16 nm, temperature from 300 to 500 K, and defect density from 0 to 0.4%, we achieve tunable control of the interfacial thermal conductance. Our study elucidates the multiscale mechanisms governing thermal transport across diamond/c-BN and provides potential pathways to actively tailor interfacial thermal properties through structural and temperature engineering. The fundamental understandings are valuable for optimizing heat dissipation and enabling thermal management solutions in next-generation power electronics leveraging these materials.