Thermal Boundary Resistance

Project Summary

We have studied the thermal boundary resistance (TBR) due to phonon boundary scattering (Kapitza effect) at a microscopically disordered interface between two crystalline solids. A formalism has been developed that is based on the Coherent Potential Approximation and vertex corrections to calculate the boundary scattering cross section on a microscopic level using empirical lattice dynamics models and Green functions techniques. The developed formalism separates the specular and diffuse channels of phonon scattering. Our work demonstrated that interface intermixing of the two materials on either side of the interface creates produce a layer with intermediate values for the acoustic impedance that facilitates the phonon transport across the interface and reduces the values of the TBR. The enhanced phonon transport across the disordered interface is realized via the diffuse channel. The results of this work are of importance to thermal transport at the nanoscale and the related issue of heat dissipation of electronic devices.

Publications

D. Kechrakos,

The role of interface disorder in the thermal boundary conductivity between two crystals,

J. Phys.: Cond. Matter 3, 1443-1452 (1991)

D. Kechrakos,

The phonon boundary cross section at disordered crystalline interfaces : A simple model,

J. Phys.: Cond. Matter 2, 2637-2652 (1990)