February 20, 2009
Colloquium Topic: Transistor Channels “Flying” a Few Nanometers Above the Surface: Novel Physics of “Empty” Space
The talk focuses on quantum-mechanical atomistic modeling of nanotube field-effect transistors on a quartz substrate. Two major results will be presented in depth, both related to unusual properties of the surface electromagnetic modes of a polar substrate. Firstly, a new thermal conductance mechanism will be determined which is due to heat exchange via virtual photons that exist only in a narrow space close to the quartz surface. Such a mechanism appears to be orders of magnitude more effective than classical thermal conduction and, therefore, to dominate thermal coupling through the channel-substrate hetero-interface. This novel effect may solve the issue of thermal interconnects in future electronics. Its implications for charge transport, both for the low-field transistor mobility and the high-field saturation regime will be detailed. Second, the same surface electromagnetic modes, for a certain crystal orientation, will be shown to produce a Casimir torque, a pure quantum electro-dynamical effect. It is not just fundamental science but practical applications which drove this study: Casimir torque is of particular interest for nanotube alignment and for large scale device fabrication in thin-film transistor technology. In addition, a vertical counterpart of the Casimir force could be potentially used to improve NEMS characteristics. The range of materials where the above effects may take place, includes but not limited to various polar substrates, like quartz, sapphire, calcite, and various nanoscale channel materials, such as nanotubes, nanowires, and graphene. Recent experimental data on alignment and transport in nanotube transistors will be discussed.
Colloquium Speaker: Slava Rotkin
Slava Rotkin is the Frank J. Feigl Junior Faculty Scholar, Assistant Professor at Physics Department and Faculty at the Center for Advanced Materials and Nanotechnology, Lehigh University. He received his M.Sc. in Optoelectronics and Electronics (Summa Cum Laude) from the Electro-Technical Institute (St. Petersburg, Russia) in 1994 and his Ph.D. in Physics and Mathematics (advisor Professor Robert A. Suris) from Ioffe Institute (St. Petersburg, Russia) in 1997. Dr. Rotkin was Research Staff Fellow at Ioffe Institute in 1994-99. He became the Beckman Fellow and, then Visiting R. A. Professor at the Beckman Institute for Advanced Science and Technology at UIUC (Urbana IL) in 2000-04. He has been at Lehigh University (Bethlehem, PA) since 2004. Dr. Rotkin is a recipient of scientific awards, including: (2007) Eleanor and Joseph F. Libsch Early Career Research Award; (2004) Frank J. Feigl Junior Faculty Scholarship; (2000) Beckman Fellowship; (1995) Royal Swedish Academy of Sciences fellowship; (1994-96) President and Government Grant for Young Scientists of Russia. He is a Member of APS, ECS, MRS, IEEE and SPIE. He is the Editor of "Research Letters in Physics" Journal, the Editor of the Springer’s book on Applied Physics of Nanotubes; the author of 50+ journal publications (and 40+ proceedings papers). Dr. Rotkin serves as the Member of the Executive Committee at the Fullerene and Nanotube Division of the ECS and Program Chair of the Nanotube Sessions (since 2001). His name is listed in Who’s Who in Science and Engineering, Who’s Who Among American Teachers and Educators and Who’s Who Emerging Leaders (since 2004).