Heat and Charge Transport and Coupling in Quantum-Confined Nanowires

CBET-1336428 PI：ChenIn介电材料，如半导体，热量通过声子（晶格振动）传导。当固体的特征长度尺度与声子波长相当时，对于大多数半导体来说，声子波长在1到10 nm的范围内，一个新的制度被称为？声子禁闭？制度产生。这一制度还有待实验，但将提供巨大的洞察力的基本原理的能量传输和转换。该项目的目标将是首次探测声子限制状态，具有以下目标：1）开发能够分辨亚皮瓦/开尔文（pW/K）热导率的高分辨率电阻测温方案，以探测直径低至5 nm的纳米线，其将具有10 pW/K量级的热导率; 2）研究声子约束下单组分和核壳结构纳米线的热输运，阐明声子约束和边界散射对热输运的影响，探索异质结构声子工程的前景; 3）研究量子限制区中的载流子和热电输运，以理解低维电荷输运和电子-声子耦合。热能传输和转换现象在各种技术中普遍存在，例如计算和通信设备中的热生成和耗散以及热电废热清除。 随着微型化趋势的持续，各种功能结构的尺寸正在接近声子波长的尺度。该项目将提高我们对量子限制机制中基本热能传输和转换过程的理解。随后，这种理解将使我们能够超越经典的尺寸效应机制来设计热和热电性能，这可能会影响重要的热技术，如隔热，热电和热管理。在这个项目中进行的研究也将培养学生在纳米科学和传热的跨学科领域。此外，参与和教育当地弱势高中和本科生的机会将通过该项目与UCSD校园的外展计划一起得到支持。

CBET- 1336428PI: ChenIn 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.