PREDICTION OF THERMAL BOUNDARY CONDUCTANCE AT THE INTERFACE WITH PHONON WAVE-PACKET SIMULATIONS: THE ROLES OF VIBRATIONAL SPECTRA DIFFERENCES, INTERFACE BOND STRENGTH, AND INELASTIC SCATTERING

摘要

The current study uses phonon wave-packet simulations and calculates the phonon transmission rate to explore the contributions of the mass and the bond energy differences on the thermal boundary conductance at the interface between two dissimilar materials. The impact of interdiffusion and interface bond strength on the thermal boundary conductance are also studied. Results show that the difference in mass and bond energy of materials results in a difference in phonon dispersion relations. Thus the frequency dependence of phonon transmission rate is observed at the interface. The interdiffusion allows high frequency phonons to contribute to phonon energy transport by inelastically scattering into multiple lower frequency phonons. Therefore the different energy distribution at the interface is observed for different wavevectors when there is interdiffusion between two materials which results in increased strain at the interface. It is also found that applying different bond strengths has little effect on thermal boundary conductance at the interface unless this interface bond strength deviates significantly from the commonly used mixing rules.