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，因此撞击会造成影响。由于这种脆性裂缝，基于硅的结构不是加工的，而是用各种巧妙的方式制造的。但是，在临界温度以上，在大约600°C下，硅硅变成了延展性，即可以塑料变形。最近的一些实验发现，即使在室温下，亚微米硅结构也会暴露出塑性变形。尽管这种依赖大小的脆性转变具有提高基于硅的纳米技术的可靠性和制造的强大潜力，但我们目前对现象的理解仍然不完整。这项赠款的目的是使用计算建模实现对单晶硅的脆性脆性转变的基本原子水平的理解。这将通过使用原子模拟再现实验观测来实现，然后分析模拟结果并构建预测性的多尺度模型。这项研究中获得的知识和理解将通过更好的设计以及成本效益的制造过程来提高无处不在的微型和纳米电子机械系统的可靠性，这将对国民经济产生重大影响，因为全球纳米技术市场估计将在2021年及其研究中涉及妇女的研究，并将其用于跨越计划。在这项研究中，将分别在辛辛那提大学的合作计划进行加速的分子动力学模拟，以揭示负责在子微米尺度下负责单晶硅单硅硅的原子尺度机制。将考虑将单一障碍物和纳米线的计算模型分析各种关键因素（例如温度，大小，几何，加载速率，自由表面结构和氧化物层）的影响。为了在近乎相同的实验条件下进行模拟，将采用一种称为“超型动力学”的加速分子动力学模拟方法以及一种空间多尺度的准循环方法。这项研究的结果将使其他脆性材料（例如蓝宝石和氧化锆的能力）的投资也是一个持续的问题。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛影响的审查标准通过评估而被视为珍贵的支持。