Phonon Heat Transport and Mechanical Oscillations in Mesoscopic Systems

9873573 Cross该奖项支持理论研究和教育，旨在研究10-100 nm长度尺度上GaAs和硅制造结构中声子和机械振荡的热传输。 微加工技术的最新进展已经允许构造绝缘或掺杂GaAs或硅的悬浮的、独立的结构。 这些结构的部分与衬底隔离，使得通向环境的唯一热路径是通过悬置梁。“这些光束是通过光刻来定义的，因此它们可以被设计为允许在介观尺度上测量热传输。 矩形截面200 × 300 nm和长度5 m的热通道已经建成，更小的宽度似乎是可行的。 这些结构的机械振荡也可以通过实验来研究。 这些进展有望首次系统地研究介观系统中声子的热输运，并进一步发展介观系统中机械振荡的研究，这是知之甚少。 PI提出了对这些问题的理论攻击。 PI计划基于Landuaer-Buttiker形式主义扩展他们最近的工作。 声子，将允许定量预测的热输运的现实模型将被使用和散射的几何形状，表面粗糙度和材料无序的影响将被包括在内。 电子-声子相互作用的影响，这也可以在实验的几何形状进行研究，将进行调查。 在低温下，包含热能的模式成为悬挂结构的机械振动模式，因此机械振动器中的热传输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，特别是这种振荡器的Q。该奖项支持基础科学和MEMS（微机电系统）相关领域的研究和教育。 PI将使用最先进的技术来研究振动和振荡以及由硅和其他材料在微米和亚微米长度尺度上制造的机械系统中的热流。

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.***