Molecular-dynamics study of energy flow and the Kapitza conductance across an interface with imperfection formed by two dielectric thin films

Cherng Jyh Twu, Jeng Rong Ho

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Abstract

A molecular-dynamics study of the flow of thermal and mechanical energies and the Kapitza conductance across both ideal and imperfect interfaces formed by two dielectric thin films is presented. The numerical experiments were achieved on a three-dimensional lattice configuration consisting of two kinds of fcc lattice particles having, respectively, Lennard-Jones and Morse interaction potentials. The degree of discrepancy between the two films was realized through altering the parameter of the interaction potential. Interfacial imperfections due to interdiffusion and a vacancy were considered. An effective computational procedure was proposed to release the initial stress induced by forming the two-layered structure. Results show that a large temperature jump occurred at the interface, and that the interfacial resistance dominated the effective conductivity of the whole film. Both the Kapitza conductance and the effective conductivity of the whole film decreased with the increase of the discrepancy between the two films, as well as decreased with the increase of the degree of disorder around the interface. With the increase of the system temperature, the temperature jump at the interface decreased and the Kapitza conductance increased. The effective conductivity, however, first increased then decreased with temperature. A peak conductivity was thus observed. The process of the energy transition for the pulsed, propagating elastic, and thermal energies, especially at the duration of passing through the interface, was demonstrated. The transmission coefficient of the energy through the interface was calculated, and the transformation of the energy from elastic to thermal was illustrated.

Original languageEnglish
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume67
Issue number20
DOIs
StatePublished - 28 May 2003

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