Silicon nanowire thermoelectrics

COMP 116

James R. Heath, heath@caltech.edu1, Akram Boukai, boukai@caltech.edu1, Yuri Bunimovich, ylb1@caltech.edu2, Jen Kan Yu1, William A. Goddard III, wag@wag.caltech.edu3, Paul von Allmen, Paul.Von.Allmen@motorola.com4, Jamil Tahir-Kheli5, Seungwon Lee3, Robert J. Nielsen, smith@wag.caltech.edu3, and Yuki Matsuda, yuki@wag.caltech.edu6. (1) Caltech Division of Chemistry and Chemical Engineering, M/C 127-72, Pasadena, CA 91125, (2) Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, (3) Materials and Process Simulation Center, California Institute of Technology, Beckman Institute (139-74), Pasadena, CA 91125, (4) Motorola Labs, 7700 South River Pkwy, Tempe, AZ 85284, (5) Materials and Process Simulation Center (MSC) (139-74), California Institute of Technology, Pasadena, CA 91125, (6) Division of Materials Science, California Institute of Technology, 1200 E. California Blvd. 139-74, Pasadena, CA 91125
Thermoelectric materials convert a temperature difference into a voltage, and so can provide for a power source with no moving parts. The optimization of a thermoelectric material involves the optimization of three different physical parameters – the thermopower (S, measured in volts per Kelvin), the electrical conductivity (s), and the inverse of the thermal conductivity (k). These different parameters are typically not independent, often frustrating the process of optimizing such materials. However, in certain cases, the ability to tune the physical dimensions of the thermoelectric material provides a powerful handle for such optimization. In this talk, we will discuss a set of experimental measurements upon silicon nanowire thermoelectrics and compare to the results of first principle predictions from theory. Separate measurements of all three critical thermoelectric parameters, coupled with the ability to tune the nanowire diameter and doping level, are beginning to reveal that high-performance thermoelectric materials can be generated from single crystal silicon.