The Molecular Dynamics Simulation And Modified Theoretical Model For Thermal Interface Conductance

Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding of interfacial thermal transport in microelectronics,photonics,and thermoelectric devices.Thermal transport across interface has been studied both experimentally and theoretically in the past.In this paper,thermal interface conductance between Aluminum and Silicon with special nanostructures was simulated using Non-equilibrium Molecular Dynamics(NEMD).By removing part of atoms at interface region,cylindrical protruding(hollow)geometry was created.Further its effect on interface conductance was investigated and the results showed that,as the removed atoms increases,the thermal interface conductance is also considerably decreased.Besides,the resistance's(1/G)dependence on system size(1/L)becomes no longer obvious linear when the interface defect is introduced,which means the linear extrapolation method is no longer applicable when interface defect is introduced.And also,it is found a larger contact area for structure with vacancy defect in Al would make a larger the thermal interface conductance than with the same defect in Si,since Al is softer and has a lower melting temperature than Si.Additionally,the acoustic mismatch model(AMM)and the diffuse mismatch model(DMM)have traditionally been used to predict the thermal interface conductance(TIC).However,the original AMM and DMM postulate that all the phonons undergo specular and diffusive transmission respectively,and are only suitable for perfectly smooth and completely disorder interfacial conditions.Therefore,constructing a general accurate model to predict the TIC is a formidable,but significant task.Here,we present a new model called the mixed mismatch model(MMM)to predict the TIC by taking both specular and diffuse transmissions into account.In our model,the relative proportions of specular and diffuse transmission are determined by the interface density of states(IDOS),so the MMM is applicable for interfaces with arbitrary roughness.Results show that our new model MMM presents a much better prediction for the TIC with different interface roughness compared with the AMM and DMM,and matches well with the MD values.