The Simple Physics of Electronic, Thermal, and Electro-thermal Transport from the Nanoscale to the Macroscale
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Our understanding of electron transport has developed, evolved, and matured step by step with the development of semiconductor technology. The field of thermal transport has an even longer history beginning with Fourier's Law, but electrons and phonons always go together "“ sometimes it is a problem, as in the self-heating of electronic devices, and sometimes it is the whole point, as in thermoelectrics. My goal is to convey in a simple and intuitive way the understanding of transport from the nanoscale to the macroscale that has developed over the past 35 years. Two examples will be discussed. The first involves nanotransistors "“ tremendously important devices that are also scientifically interesting. Nanoscale transistors operate much differently than their microscale counterparts, but the essential physics is not at all complicated. I'll discuss the operation of these devices in a way that is much different than what you'll find in textbooks, but actually much simpler. The second example concerns one of the first semiconductor technologies, thermoelectrics. Progress stalled in the 1960's, but new ideas have led to significant advances over the past 20 years. The field is often considered to be complicated, both in terms of mathematics and in the detailed trade-offs involved. I'll show how the general approach developed for electronic transport is applied to this problem. I'll show that the thermoelectric figure of merit depends solely on the ratio of the electrical to thermal conductivity, which helps explain why it has been so hard to increase zT. The broader goal of this talk is to show how, in an age of specialization that drives progress in research, we can avoid being splintered into groups of specialists who know more and more about less and less.
MARK LUNDSTROM is the Don and Carol Scifres Distinguished Professor of Electrical and Computer Engineering at Purdue University. His teaching and research center on the physics, technology, modeling and simulation of electronic devices. Lundstrom was the founding director of the NSF-funded Network for Computational Nanotechnology, which created nanoHUB.org, now a global resource for nanotechnology. His research currently focuses on electro-thermal transport in semiconductors and on thermoelectric devices. Lundstrom also directs the nanoHUB-U online educational initiative and is editor-in-chief of the "Lessons from Nanoscience" lecture notes series with World Scientific. He is a member of the U.S. National Academy of Engineering, a Life Fellow of the IEEE, and a fellow of the APS, and AAAS. Lundstrom is the 2018 recipient of the IEEE Leon K. Kirchmayer Graduate Teaching Award.