Phonon Heat Transport and Mechanical Oscillations in Mesoscopic Systems

9873573Cross该奖项支持旨在研究10-100 nm尺度上的声子和机械振荡在制造结构中的热传输的理论研究和教育。微细加工技术的最新进展使绝缘或掺杂的砷化镓或硅的悬浮、独立结构的建造成为可能。这些结构的一部分与衬底隔绝，因此通往环境的唯一热路径是通过悬挂的“梁”。这些光束是用光刻技术定义的，因此它们可以被设计成允许在介观尺度上测量热传输。已经建立了矩形截面200×300 nm、长度5m的热路径，而且宽度似乎更小是可行的。这些结构的机械振动也可以通过实验进行研究。这些进展预示着首次系统研究介观系统中声子的热输运，并进一步发展对介观系统中机械振荡的研究，这方面的了解还很少。PI对这些问题提出了理论上的攻击。PI计划扩展他们最近基于Landuaer-Buttiker形式主义的工作。将使用能够定量预测热传输的声子的真实模型，并将包括几何散射、表面粗糙度和材料无序的影响。电子-声子相互作用效应也可以在实验几何学中研究，我们将对此进行研究。在低温下，含有热能的振型成为悬置结构的机械振动模式，因此对机械振子中的热输运和耗散的研究变得密切相关。因此，有可能将理论研究扩展到介观振荡器，特别是此类振荡器的Q。%该奖项支持基础科学和与MEMS(微电子机械系统)相关的领域的研究和教育。PI将使用最先进的技术来研究微米和亚微米长度尺度上由硅和其他材料制造的机械系统中的振动和振荡以及热量的流动。

9873573CrossThis award supports theoretical research and education that aims to investigate the transport of heat by phonons and mechanical oscillations in fabricated structures of GaAs and silicon on the 10-100 nm length scale. Recent advances in microfabrication techniques have allowed the construction of suspended, free-standing structures of insulating or doped GaAs or silicon. Portions of these structures are isolated from the substrate so that the only thermal pathway to the environment is through the suspension "beams." These beams are defined lithographically, so they can be designed to allow measurements of thermal transport at the mesoscopic scale. Thermal pathways of rectangular cross-section 200 X 300 nm and length 5m have already been constructed, and much smaller widths seem feasible. The mechanical oscillations of these structures can also be studied experimentally. These advances promise the first systematic investigation of heat transport by phonons in mesoscopic systems, and further development in the study of mechanical oscillations in mesoscopic systems which is poorly understood. The PI proposes a theoretical attack on these problems. The PI plans to extend their recent work based on the Landuaer-Buttiker formalism. Realistic models of phonons that will allow the quantitative prediction of thermal transport will be used and the effects of scattering by geometry, surface roughness, and material disorder will be included. Electron-phonon interaction effects, which can also be studied in experimental geometries, will be investigated. At low temperatures, the modes containing the thermal energy become the mechanical oscillation modes of the suspended structures, so that studies of heat transport and dissipation in mechanical oscillators becomes closely related. Thus it is possible to extend the theoretical investigation to mesoscopic oscillators, and in particular the Q of such oscillators.%%%This award supports research and education in an area that is both fundamental science and related to MEMS (microelectromechanical systems). The PI will use state of the art techniques to study vibrations and oscillations and the flow of heat in mechanical systems fabricated from silicon and other materials on micron and sub-micron length scales.***