Heat and Charge Transport and Coupling in Quantum-Confined Nanowires

University Of California-San Diego, La Jolla CA

Investigators

Abstract

CBET- 1336428 PI: Chen In dielectric materials, such as semiconductors, heat is conducted by phonons (lattice vibrations). When the characteristic length scale of a solid is comparable to phonon wavelength, which for most semiconductors is in the range of 1 to 10 nm, a new regime referred to as the ?phonon confinement? regime arises. This regime has yet to be accessed experimentally but will provide tremendous insight into the fundamentals of energy transport and conversion. The goal of this project will be to probe the phonon confinement regime for the first time with the following objectives: 1) Develop a high-resolution resistive thermometry scheme capable of resolving sub-picowatt/Kelvin (pW/K) thermal conductance, in order to probe nanowires with diameter down to 5 nm, which will possess thermal conductance on the order of 10 pW/K; 2) Study thermal transport in single-component and core-shell nanowires in the phonon confinement regime, in order to elucidate the effects of confinement and boundary scattering on thermal transport, as well as explore the prospect of phononic engineering through heterostructures; 3) Investigate carrier and thermoelectric transport in the quantum confinement regime to understand low dimensional charge transport and electron-phonon coupling. Thermal energy transport and conversion phenomena are ubiquitous in a variety of technologies, such as heat generation and dissipation in computing and communication devices and thermoelectric waste heat scavenging. As the trend of miniaturization continues, the size of various functional structures is approaching the scale of phonon wavelength. This project will enhance our understanding of fundamental thermal energy transport and conversion processes in the quantum confinement regime. Subsequently, this understanding will enable us to engineer thermal and thermoelectric properties beyond the classical size effect regime, which could impact important thermal technologies such as thermal insulation, thermoelectrics, and thermal management. The research undertaken in this project will also train students in the interdisciplinary fields of nano-science and heat transfer. Furthermore, opportunities to engage and educate local disadvantaged high school and undergraduate students will be supported through this project in conjunction with outreach programs at the UCSD campus.