Modeling and Characterization of SiGe Nanocomposite

Dr. Hohyun Lee
Department of Mechanical Engineering
Santa Clara University

Direct energy conversion between thermal and electrical energy based on thermoelectric  effects  is  attractive  for  potential  applications  in  waste  heat recovery  and  environmentally-friendly  refrigeration.    The  energy  conversion efficiency  depends  on  the  dimensionless  figure  of  merit  of  thermoelectric materials, ZT, which is proportional to the electrical conductivity, the square of the Seebeck coefficient, and the inverse of the thermal conductivity.  Currently, the low ZT  values  of  available  materials  restrict  the  efficient  applications  of  this technology.  Recently,  significant enhancements in ZT have  been reported in nanostructured materials such as superlattices mainly due to their low thermal conductivities.  The reduced thermal conductivity of nanostructures is mainly attributed to the large number of interfaces at which phonons are scattered.  Based on this idea, nanocomposites are expected to have a lower thermal conductivity than their bulk counterparts with low fabrication cost just by mixing nano sized particles.    This  talk  will  discuss  mechanisms  of  thermoelectric  transport  via modeling  and  provide  experimental  evidence  on  the  enhancement  of thermoelectric figure of merit in SiGe nanocomposites.

Dr. Hohyun Lee received his Ph.D. degree in Mechanical Engineering from the Massachusetts Institute of Techonology in 2009. His research interests include charge  &  energy  transport  phenomena  in  nanostructures,  temperature management in thermal systems, energy harvesting for health monitoring devices, and water purification. Currently, he is an Assistant Professor in the Department of Mechanical Engineering at Santa Clara University.