Impedance Matching of Atomic Thermal Interfaces Using Primitive Block Decomposition

Abstract

We explore the physics of thermal impedance matching at the interface between two dissimilar materials by controlling the properties of a single atomic mass or bond. The maximum thermal current is transmitted between the materials when we are able to decompose the entire heterostructure solely in terms of primitive building blocks of the individual materials. Using this approach, we show that the minimum interfacial thermal resistance arises when the interfacial atomic mass is the arithmetic mean, whereas the interfacial spring constant is the harmonic mean of its neighbors. The contact-induced broadening matrix for the local vibronic spectrum, obtained from the self-energy matrices, generalizes the concept of acoustic impedance to the nonlinear phonon dispersion or the short-wavelength (atomic) limit.

Keywords:

• Phonon transport
• Phonon NEGF
• atomic interfaces
• interfacial forces
• adhesion

Acknowledgments

C.A.P. thanks Professor Peter Arnold and Dr. John Duda for the useful discussions. C.A.P. and A.W.G. are grateful for the support from NSF-CAREER (QMHP 1028883). C.A.P., A.W.G., and P.E.H. are greatly appreciative for the funding from NSF-IDR (CBET 1134311). P.E.H. is thankful for the funding from the LDRD program office at Sandia National Laboratories.