Temperature Effect on Advanced Mechanical Properties of Semiconductor Nanowires

半导体纳米线是许多纳米技术应用的主要组成部分，包括电子学、传感器、光电子学以及能量收集和存储。这种纳米器件的超大规模集成导致了高功率密度和高工作温度。虽然半导体纳米线非常重要，但目前对高温下半导体纳米线的机械性能缺乏基本的了解。本课题旨在开发基于微机电系统（MEMS）的片上热力学测试平台，利用原位透射电子显微镜（TEM）对半导体纳米线进行热力学测试。具体来说，本课题将研究温度以及其他基本参数（尺寸、表面积体积比、轴向和表面取向）对ZnO纳米线的力学性能（包括相变）的影响。如果成功，该研究将为理解纳米相变做出基础性贡献。实验结果将被广泛传播，以促进与原子模拟的合作，以确定尺寸对这种行为的影响。此外，在这个项目中开发的新实验工具将使广泛的纳米结构（如硅纳米线）的热机械特性控制成为可能。建议的工作将与一些教育活动紧密结合，包括：1)培养研究生进行多学科研究；2)整合PI在NCSU提供的本科和研究生课程的研究，并在网络上传播新的课程模块；3)本科生特别是女性和少数族裔参与MEMS和纳米力学的跨学科研究；4)与NCSU的工程场所项目合作，参加夏令营和组织高中教师研讨会。

Semiconductor nanowires are major building blocks for many nanotechnology applications including electronics, sensors, optoelectronics, and energy harvesting and storage. The ultra-large-scale integration of such nanodevices leads to high power density and thus high operating temperature. Though very important, fundamental understanding on the mechanical properties of semiconductor nanowires at high temperature is currently lacking. The objective of this proposal is to develop an on-chip thermomechanical testing stage based on microelectromechanical systems (MEMS) and carry out thermomechanical testing of semiconductor nanowires by in-situ transmission electron microscopy (TEM). Specifically, this proposal will investigate the effect of temperature as well as other fundamental parameters (size, surface area to volume ratio, axial and surface orientations) on mechanical properties including phase transformation of ZnO nanowires.If successful, the proposed research will make fundamental contributions to understanding the nanoscale phase transformation. The experimental results will be widely disseminated to facilitate collaboration with atomistic simulations to pin down the size effects on this behavior. In addition, the new experimental tools developed in this project will enable controlled thermomechanical characterization of a broad range of nanostructures such as silicon nanowires. The proposed work will be closely integrated with several educational activities including: 1) training of graduate students for multidisciplinary research; 2) integration of research into undergraduate and graduate courses that PI offers at NCSU, and web-based dissemination of the new course module; 3) Involvement of undergraduate students especially women and underrepresented minorities in the interdisciplinary research in MEMS and nanomechanics; 4) Collaboration with the Engineering Place program at NCSU by participating in the summer camps and organizing high school teacher workshops.