Molecular-dynamics Study of Thermal Boundary Resistance: Evidence of Strong Inelastic Scattering Transport Channels

With the ever-decreasing size of microelectronics, growing applications of superlattices, and development of nanotechnology, thermal resistances of interfaces are becoming increasingly central to thermal management. Although there has been much success in understanding thermal boundary resistance (TBR) at low temperature, the current models for room temperature TBR are not adequate. This work examines TBR using molecular dynamics (MD) simulations of a simple interface between two FCC solids. The simulations reveal a temperature dependence of TBR, which is an indication of inelastic scattering in the classical limit. Introduction of point defects and lattice-mismatch-induced disorder in the interface region is found to assist the energy transport across the interface. This is believed to be due to the added sites for inelastic scattering and optical phonon excitation. A simple MD experiment was conducted by directing a phonon wave packet towards the interface. Inelastic scattering, which increases transport across the interface, was directly observed. Another mechanism of energy transport through the interface involving localization of optical phonon modes at the interface was also revealed in the simulations.