University of California, Riverside

Department of Electrical and Computer Engineering



Thermoelectric Properties of the Bi and Bi2Te3 Nanowires


Thermoelectric Properties of the Bi and Bi2Te3 Nanowires
 

 By

Dr. Igor Bejenari

University of California, Riverside
Department of Electrical Engineering

When: Tuesday, February 3, 2009
Time: 2:00pm - 3:00pm
Location: A265 Bourns Hall

Abstract:

The study of nanowire systems is of interest because of their possible applications in high efficiency thermoelectric devices, like scanning thermal microscope, thermoelectric micro-generators, thermoelectric cooling micro-devices etc. The strong two-dimensional confinement of such systems allows manipulating kinetic effects. The most promising thermoelectric elements are those based on the nanostructures consisting of anisotropic materials such as bismuth, bismuth telluride, and lead tellurides. Bismuth telluride and its solid solutions (Bi2-xSbxTe3 and Bi2Te3-ySey) are presently the best thermoelectric materials for commercial applications at room temperature. The charge carrier effective-mass anisotropy enhances the carrier confinement effect and complicates the carrier motion through a cross section of the nanowire. The anisotropy factor leads to a modification of physical properties of the nanowire. For instance, the semimetal-semiconductor transition takes place at the Bi nanowire diameter dependent on the effective-mass anisotropy. In addition to the confinement effect, the electric field effect (EFE) presents the other powerful tool for modifying thermoelectric properties of the low dimensional structures by means of the influence on the Fermi level position. The EFE is more significant in wire (co-axial) structures than in planar structures due to both the cylindrical configuration and the larger ratio surface/bulk.

About the Speaker:

Igor Bejenari received his Ph.D. degree in Physics and Mathematics from the Institute of Applied Physics, Academy of Sciences of Moldova in 2006. He received his M.S. degree in Physics in the Moldova State University in 1995. He was a visiting fellow at the Warwick University (UK) in 2002 and at the Bogolubov Laboratory of Theoretical Physics, Joint Institute of Nuclear Research (Russia) in 2007. His current research interests include electronic and optical properties of semiconductor nanowires and graphene. One of his papers devoted to the research of the electronic band structure of bismuth nanowires was chosen by the Editors of the Institute of Physics (IOP) for its novelty, significance and potential impact on future research in 2004. He received the Fulbright Research Scholar award in 2008 and the Royal Society award in 2002.

 

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