Fundamentals of Heterogeneous Nucleation with Application to the Optimization of Horizontal Ribbon Growth

异质成核的基础及其在水平带生长优化中的应用

• 批准号: 2317674
• 负责人: Brian Helenbrook
• 金额: $ 55.41万
• 依托单位: Clarkson University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-11-01 至 2026-10-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2317674&HistoricalAwards=false
• 关键词: Fundamentals; Heterogeneous; Nucleation; Application; Optimization

This award supports research into new models of solidification kinetics and employs them to optimize the horizontal ribbon growth (HRG) process. HRG is a technique for producing thin wafers of single-crystal silicon for use in solar cells, which has the potential to significantly lower production costs (possibly 75% lower) compared to currently used techniques. Commercialization has not yet been successful mainly because of a lack of understanding of the solidification dynamics. New models enable the prediction of currently unexplained phenomena observed in HRG experiments. The models have the potential to impact crystal growth processes beyond HRG, leading to new applications with materials other than silicon such as sapphire or germanium. This work will provide deeper insights into the fundamentals of crystal growth and accelerate the development of new growth techniques, which will in turn help the US to achieve energy independence using renewable resources and grow advanced manufacturing in the US.Current theories for 2D Nucleation are derived assuming the nucleation occurs in a uniform environment with an infinite area, which always results in polynuclear growth. However, in all realistic growth processes, there are always temperature variations that limit the area where 2D nucleation will occur. The effect of these temperature variations will be investigated using Monte Carlo and Molecular Dynamic simulations, the results of which will be used to develop a new 2D nucleation model. This model will predict 2D nucleation and step propagation in spatially varying temperature fields without a-priori assuming polynuclear growth. This model will be incorporated into high-order accurate finite element simulations of the HRG process. These continuum simulations will predict the onset of 2D and 3D flow and solidification instabilities and their impact on the growth process. They will be used to optimize the process to enable the production of uniform, thin silicon wafers, at a high production rate.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.

该奖项支持对新的凝固动力学模型的研究，并利用它们来优化水平带状生长(HRG)过程。HRG是一种用于生产用于太阳能电池的单晶硅薄片的技术，与目前使用的技术相比，这种技术有可能显著降低生产成本(可能降低75%)。商业化尚未成功，主要是因为缺乏对凝固动力学的了解。新的模型能够预测目前在HRG实验中观察到的无法解释的现象。这些模型有可能影响HRG以外的晶体生长过程，导致蓝宝石或锗等硅以外材料的新应用。这项工作将为晶体生长的基本原理提供更深入的见解，并加速新生长技术的开发，这反过来将有助于美国利用可再生资源实现能源独立，并在美国发展先进制造业。目前的2D成核理论是假设成核发生在具有无限面积的均匀环境中，这总是导致多核生长。然而，在所有现实的生长过程中，总有温度变化限制了2D形核发生的区域。这些温度变化的影响将用蒙特卡罗和分子动力学模拟来研究，其结果将被用来开发一个新的2D成核模型。该模型可以预测二维形核和在空间变化的温度场中的阶跃传播，而无需先验假设多核增长。该模型将被纳入高精度的HRG过程有限元模拟中。这些连续介质模拟将预测2D和3D流动和凝固不稳定性的开始及其对生长过程的影响。他们将被用来优化工艺，以实现以高生产率生产均匀、薄的硅片。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。