(630c) Thermal and Thermoelectric Transport in Semiconductor Nanowires

Semiconductor nanostructures are ubiquitous in electronic devices. Thermal transport plays an important and sometimes pivotal role in the performance of these devices. For instance, thermal coupling between nano-scale transistors and the surrounding materials would dictate the heat dissipation of the transistors. Thermal conductivity is an important parameter to engineer to enhance energy conversion efficiency of thermoelectric devices. During the past decade, we have witnessed tremendous efforts devoted to the understanding and manipulation of thermal transport properties in semiconductor nanostructures, including thin films, superlattices, nanowires and nano-composites. However, most of these studies have been focused on the classical size regime where the characteristic sizes of nanostructures are greater than dominant phonon wavelength. As the size of nanostructures keeps shrinking and becomes comparable to phonon wavelength, the quantum confinement effect would emerge. Exact picture of phonon transport in this new regime, however, is not fully explored. In this presentation, we use semiconductor nanowires with ultra-small diameters as a model system to explore the quantum confinement effect on thermal and thermoelectric transport. We will present experimental techniques we have developed recently to probe thermal and thermoelectric transport properties in thin nanowires and the new understanding obtained from these experimental studies.