Woodruff School of Mechanical Engineering

COE/Structural Mechanics Seminar


Phonon Transport in Semiconductor Superlattices


Prof. Alan McGaughey


Carnegie Mellon University


Thursday, September 3, 2009 at 3:00:00 PM


MRDC Building, Room 4211


Zhuomin Zhang


A superlattice is a periodic nanostructure built from epitaxial material layers with thicknesses as small as a few nanometers. Heat transfer in a semiconductor superlattice is due to phonons, quanta of energy associated with lattice vibrations. The length scales in a superlattice may be smaller than the bulk phonon mean free paths of the constituent materials. In such cases, continuum relations such as the Fourier law and the heat conduction equation cannot be applied to model thermal transport. Atomistic treatments are needed. In this seminar, I will describe my groupís work using molecular dynamics simulations and lattice dynamics calculations to understand phonon transport in superlattices built from silicon and germanium. I will first describe how the thermal conductivities of Si/Ge and Si/Si1-xGex superlattices are affected by interface quality. I will then look more closely at the phonon transport across individual interfaces by examining a series of theoretical models for predicting interface thermal resistance and discussing the appropriateness of the underlying assumptions in each. The seminar will conclude with a discussion about how the analysis of a nanostructure with a small number of interfaces can be extrapolated to obtain the behavior of a periodic superlattice


Alan McGaughey is an Assistant Professor in the Department of Mechanical Engineering at Carnegie Mellon University and the Struminger Junior Faculty Fellow for 2009. He holds B. Eng, M. A. Sc., and Ph. D. degrees in mechanical engineering from McMaster University, the University of Toronto, and the University of Michigan. Before starting at Carnegie Mellon in 2005, he spent a year as a post-doctoral fellow in the Materials Science and Engineering Department at the University of Florida. His research group, the Nanoscale Transport Phenomena Laboratory applies a variety of simulation and theoretical tools to model the transport of heat, momentum, mass, and charge at the atomic-level. They are supported by the Department of Energy, the National Science Foundation, and the Pennsylvania Infrastructure Technology Alliance.


Refreshments will be served.
If you are interested in meeting Professor McGaughey
please contact Dr. Zhang.