Nam Q. Le’s paper published in Journal of Applied Physics – Congrats Nam!

Our paper, “Strategies for tuning phonon transport in multilayered structures using a mismatch-based particle model,” was recently published in the Journal of Applied Physics (J. Appl. Phys. 111, 084310 (2012)). In this work we developed a thermal mismatch model (TMM) based on thermal impedance of material to predict the phonon transmission across solid interfaces.  Using a particle based interference model, this TMM was extended to multilayer systems showing excellent agreement with more-computationally-expensive wave-packet simulations.  This work was in collaboration with Pam Norris’ group and Thomas Beechem at Sandia National Laboratories.

Abstract

The performance of many micro- and nanoscale devices depends on the ability to control interfacial thermal transport, which is predominantly mediated by phonons in semiconductor systems. The phonon transmissivity at an interface is therefore a quantity of interest. In this work, an empirical model, termed the thermal mismatch model, is developed to predict transmissivity at ideal interfaces between semiconductor materials, producing an excellent agreement with molecular dynamics simulations of wave packets. To investigate propagation through multilayered structures, this thermal mismatch model is then incorporated into a simulation scheme that represents wave packets as particles, showing a good agreement with a similar scheme that used molecular dynamics simulations as input [P. K. Schelling and S. R. Phillpot, J. Appl. Phys. 93, 5377 (2003)]. With these techniques validated for both single interfaces and superlattices, they are further used to identify ways to tune the transmissivity of multilayered structures. It is shown that by introducing intermediate layers of certain atomic masses, the total transmissivity can either be systematically enhanced or reduced compared to that of a single interface. Thus, this model can serve as a computationally inexpensive means of developing strategies to control phonon transmissivity in applications that may benefit from either enhancement (e.g., microelectronics) or reduction (e.g., thermoelectrics) in thermal transport.

The Hopkins Lab was supported by a LDRD initiative through Sandia National Labs for this work.