Heat and Charge Transport and Coupling in Quantum-Confined Nanowires

CBET-1336428PI：Chenin介电材料，如半导体，热由声子(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，一种新的制度被称为声子限制？政权出现了。这一制度尚未进入实验阶段，但将为能源运输和转换的基本原理提供巨大的洞察力。本项目的目标是首次探索声子禁闭机制，目标如下：1)发展一种能够分辨亚皮瓦/开尔文(PW/K)热导的高分辨率电阻测温方案，以探测直径达5 nm的纳米线，其热导将达到10PW/K数量级；2)研究声子禁闭机制下单组分和核壳纳米线中的热输运，以阐明禁闭和边界散射对热输运的影响，并探索通过异质结构进行声子工程的前景；3)研究量子限制区的载流子和热电输运，以了解低维电荷输运和电子-声子耦合。热能传输和转换现象普遍存在于各种技术中，如计算和通信设备中的发热和散热以及热电废热的清除。随着小型化趋势的继续，各种功能结构的尺寸正在接近声子波长的规模。这个项目将加深我们对量子限制下基本热能输运和转换过程的理解。随后，这种理解将使我们能够设计超出经典尺寸效应范围的热和热电性能，这可能会影响重要的热技术，如隔热材料、热电和热管理。该项目开展的研究还将在纳米科学和传热学的跨学科领域培训学生。此外，通过该项目与加州大学圣迭戈分校校园的外展计划，将支持参与和教育当地弱势高中和本科生的机会。

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.