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构件，包括电子学、传感器、光电子学以及能量采集和存储。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。虽然半导体纳米线在高温下的力学性质非常重要，但目前还缺乏对其力学性质的基本了解。该方案的目标是开发一种基于微电子机械系统(MEMS)的片上热机械测试平台，并利用原位透射电子显微镜(TEM)对半导体纳米线进行热机械测试。具体地说，这项研究将研究温度以及其他基本参数(尺寸、比表面积与体积比、轴向和表面取向)对包括相变在内的氧化锌纳米线力学性能的影响。如果成功，这项研究将为理解纳米级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，以确定这种行为的尺寸效应。此外，在该项目中开发的新的实验工具将能够对广泛的纳米结构进行受控的热机械表征，例如硅纳米线。拟议的工作将与几项教育活动密切结合起来，包括：1)培训研究生进行多学科研究；2)将研究纳入国立CSU的本科生和研究生课程，并通过网络传播新的课程模块；3)本科生，特别是女性和代表性不足的少数群体参与MEMS和纳米机械方面的跨学科研究；4)通过参加夏令营和组织高中教师讲习班，与NCSU的工程场所计划合作。

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.