Experimental Investigation of Fundamental Mechanical Behavior of Silicon Nanowires

本文研究了硅纳米线的尺寸效应对其弹性、断裂和脆韧转变的影响。将对同一块NWs进行原位扫描/透射电镜共振和拉伸测试，以测量其弹性行为。在实时和死后显微镜分析的帮助下，将采用统计的weibull型概率模型来分析裂缝数据并确定裂缝起源。原位热力学测试在现场进行，在透射电子显微镜下使用一种新的微加工测试平台，将用于探测脆性到韧性的转变。如果成功，这项研究有可能改善柔性和可拉伸的电子产品，改善能量转换和存储。预计实验结果将以协作的方式用于开发原子模拟，以确定纳米级弹性，断裂和脆性到韧性转变的基本机制。此外，本项目开发的新型实验工具和方法（例如，微加工热机械测试阶段）可用于了解各种纳米结构的性质。从教学角度来看，这项工作将：1)整合到PI在NCSU提供的本科和研究生课程中（包括NSF支持的本科纳米技术实验课程），并在网络上传播新的课程模块；2)用于培训研究生和本科生进行多学科研究，有妇女和代表性不足的少数民族参与；3)用于与北卡罗莱纳州立大学的工程场所项目合作，开发一个交互式演示模块，并将其呈现给K-12学生。

This research is about the correlation between the size effects of silicon nanowires on elasticity, fracture, and their brittle to ductile transition.. In-situ scanning/transmission electron microscopy resonance and tensile testing on the same single NWs will be conducted to measure the elastic behavior. A statistical, Weibull-type, probability model will be employed to analyze the fracture data and identify fracture origins with the assistance of real-time and post-mortem microscopy analyses. In-situ thermomechanical testing done in-situ, in a Transmission Electron Microscope using a novel microfabricated testing stage will be used to probe the brittle to ductile transition.If successful, the proposed research has potential to improve flexible and stretchable electronics, improve energy conversion and storage. It is anticipated that the experimental results will be used in a collaborative way to develop atomistic simulations that will pin down the mundamental mechnisms of nanoscale elasticity, fracture and brittle to ductile transition. In addition, the novel experimental tools and methods developed in this project (e.g., the microfabricated thermomechanical testing stage) can be used to understand the properties of a broad range of nanostructures. From a teaching perspective, this work will be: 1) integrated into undergraduate and graduate courses that PI offers at NCSU (including a NSF supported undergraduate nanotechnology laboratory course), and web-based dissemination of the new course module; 2) used for training of graduate and undergraduate students for multidisciplinary research with involvement of women and underrepresented minorities; 3) used for collaboration with the Engineering Place program at North Carolina State University to develop an interactive demonstration module and present it to K-12 students.