Phonons are the principal carriers of thermal energy in semiconductors and insulators, and they serve a vital role in dissipating heat produced by scattered electrons in semiconductor devices. Despite the importance of phonons, rigorous understanding and inclusion of phonon dynamics in simulations of modern electronic devices is very challenging, particularly because spatial confinement tends to complicate their dispersion, or frequency-wavelength, characteristics. This seminar will first provide a foundational description of phonon dynamics using a simple 1D atomic chain as an example. Then, a parallel treatment of phonon dynamics using an atomistic Green’s function (AGF) approach will be presented to demonstrate its ability to replicate canonical results. Subsequently, results from the AGF method applied to heterogeneous atomic chains, planar interfaces, and superlattices will be presented to illustrate the utility of the approach in more practical situations.
Tim Fisher joined Purdue’s School of Mechanical Engineering in 2002 after serving as a faculty member at Vanderbilt University beginning in 1998. He received the BS and PhD degrees from Cornell University and spent two years as a full-time engineer at Motorola. His work has been recognized through a number of awards, including the NSF CAREER award, the 3M Untenured Faculty Award, the Best Student Poster Award from the Semiconductor Research Corporation, and the Best Paper Award at the Fifth Intersociety Conference on Thermal Phenomena in Electronic Systems. His current research efforts include theoretical, computational and experimental studies focused toward integration of nanoscale materials with bulk materials for enhancement of electrical, thermal, and mass transport characteristics. Applications of his work cover a broad range of areas, including nanoelectronics, thermal and electrical interface materials, electronics cooling, direct energy conversion, biosensors, and hydrogen storage. This work has also produced related studies of controlled synthesis of nanomaterials, particularly carbon nanotubes.
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