Investigation of the Room Temperature Brittle-to-Ductile Transition of Single-Crystal Silicon at Sub-Micron Length Scale Using Accelerated Molecular Dynamics

利用加速分子动力学研究亚微米长度尺度单晶硅的室温脆性转变

• 批准号: 1940614
• 负责人: Woo Kyun Kim
• 金额: $ 28.77万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1940614&HistoricalAwards=false
• 关键词: Investigation; Room; Temperature; Brittle; Ductile

As is well-known, silicon is brittle so that it shatters on impact. Due to this brittle fracture, silicon-based structures are not machined, but fabricated in a variety of artful ways. Above a critical temperature though, at about 600 °C for bulk silicon, silicon becomes ductile, i.e., it can deform plastically. Several recent experiments have found that sub-micron silicon structures exhibit plastic deformation even at room temperature. While this size-dependent brittle-to-ductile transition has a strong potential to improve the reliability and manufacturability of silicon-based nanotechnology, our current understanding of the phenomenon remains incomplete. The objective of this grant is to achieve a fundamental atomic-level understanding of the size-dependent brittle-to-ductile transition of single-crystal silicon using computational modeling. This will be accomplished by reproducing the experimental observations with atomistic simulations and then analyzing the simulation results and constructing predictive multiscale models. The knowledge and understanding obtained in this research will improve the reliability of the ubiquitous micro- and nano-electro-mechanical systems through better designs as well as cost-efficient manufacturing processes, which will have significant impact on the national economy as the global nanotechnology market is estimated to reach $90.5 billion by 2021. This grant will also be used to engage undergraduates in research by leveraging the women in science and engineering summer research program and the co-op program, respectively, at the University of Cincinnati.In this study, accelerated molecular dynamics simulations will be performed to unveil the atomic-scale mechanisms responsible for the room-temperature plastic deformation of single-crystal silicon at sub-micrometer scale. Computational models of single-notched blocks and nanowires will be considered to analyze the effects of various key factors such as temperature, size, geometry, loading rate, and free surface structures and oxide layers. To carry out the simulations under near-identical experimental conditions, an accelerated molecular dynamics simulation method called hyperdynamics as well as a spatial multi-scale quasi-continuum method will be employed. The outcomes of this research will enable investigation of other brittle materials such as sapphire and zirconia whose machinability has also been an ongoing issue.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

众所周知，硅很脆，因此在受到冲击时会碎裂，因此硅基结构无法进行机械加工，而是在高于临界温度（约 600 °C）时以各种巧妙的方式制造。对于块状硅，硅变得具有延展性，即它可以塑性变形，即使在室温下，亚微米硅结构也表现出塑性变形。脆性到韧性的转变具有提高硅基纳米技术的可靠性和可制造性的巨大潜力，但我们目前对该现象的理解仍然不完整，这项资助的目的是实现对尺寸依赖性的基本原子级理解。使用计算模型实现单晶硅的脆性到延性转变，这将通过原子模拟再现实验观察，然后分析模拟结果并构建预测多尺度模型来完成。将通过更好的设计以及具有成本效益的制造工艺来提高无处不在的微纳米机电系统的可靠性，这将对国民经济产生重大影响，因为全球纳米技术市场预计到 2021 年将达到 905 亿美元这笔赠款还将用于通过辛辛那提大学的女性科学与工程暑期研究计划和合作项目来吸引本科生参与研究。在这项研究中，将进行加速分子动力学模拟。为了揭示亚微米级单晶硅室温塑性变形的原子尺度机制，将考虑单缺口块和纳米线的计算模型来分析各种关键因素的影响，例如温度、为了在几乎相同的实验条件下进行模拟，采用了一种称为超动力学的加速分子动力学模拟方法以及空间多尺度。这项研究的成果将有助于对蓝宝石和氧化锆等其他脆性材料的研究，这些材料的可加工性也是一个持续存在的问题。该奖项反映了 NSF 的法定使命，并通过使用评估被认为值得支持。基金会的智力价值和更广泛的影响审查标准。