Collaborative Research: Nanoscale Heterostructures and Defects in Two-Dimensional Materials

对应用于各种技术的材料的研究是由提高速度、提高效率和降低功耗的需要驱动的。这项研究使许多研究人员开始考虑原子薄的二维系统。这种系统具有新颖的特性，在电子和光子器件以及传感和催化方面有许多可能的应用。最近，研究人员发现，将各种二维材料组合在同一平面或堆叠层中，为瞄准和增强特定材料的应用特性打开了大门。pi计划开发计算效率高的模型来研究和预测这种系统的生长和特性。更具体地说，这项研究将涉及确定这些系统中的缺陷如何改变材料特性，因为众所周知，缺陷在决定功能方面起着重要作用。这项研究还将包括了解在生长和制造过程中缺陷是如何自然发生的，以便确定生产高质量材料系统和应用所需的无缺陷结构的最佳方法。该项目支持在尖端材料物理研究方面的研究生的培训和教育，并通过这些教育活动为具有全球竞争力和多样化的劳动力做出贡献。该项目将涉及不同科学学科的广泛国际合作。外展活动将在底特律一所女子公立学校进行，为少数族裔女性学生提供急需的K-12科学教育。该项目支持理论和计算研究与教育的整合，以模拟和预测二维（2D）材料中的新型异质结构和复杂缺陷，并了解潜在的基本机制。本研究的重点是研究平面内的二维和平面外的准二维异质结构，纳米尺度的图案，以及在单组分和多组分二维材料的生长和组装过程中出现的复杂拓扑缺陷。特别令人感兴趣的是石墨烯、六方氮化硼和过渡金属二硫化物等。基于相场晶体方法及其振幅公式的预测模型，结合微观和介观尺度，将开发用于研究这些基本重要的纳米结构和缺陷的结构和动力学特性。这些方法结合了材料的弹性、可塑性和原子细节，如位错、晶界和大长度和时间尺度上的三重结，这是传统原子技术无法实现的。所开发的模型将用于预测微观结构的形成和形态和成分调制的界面纳米模式的动力学，以及复杂缺陷的形成、运动和影响。例子包括由不同类型的二维材料组成的面内横向异质结和受三维和变形影响的面外异质结构。生长机制也将被研究，以确定可控合成所预测的纳米异质结构的最佳条件。该研究将为这些低维材料结构发展的基本机制，特别是微观和中观尺度之间的耦合机制以及各种生长和加工条件的影响提供新的见解。该研究还将能够调查和预测这些新型二维系统的新热学和电子特性，目标是将微观结构与材料特性以及加工条件联系起来。该项目将通过培训和教育学生进行尖端研究，并将涉及不同科学学科的广泛国际合作，为全球竞争力和多样化的劳动力做出贡献。此外，还将开展外展活动，以加强对底特律一所女子公立学校中代表性不足的少数民族学生的K-12科学教育。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThe search for materials with applications in various types of technologies is driven by the need to increase speed, improve efficiency, and reduce power consumption. This search has led many researchers to consider atomically thin two-dimensional systems. Such systems have novel properties with many possible applications in electronic and photonic devices as well as in sensing and catalysis. Recently, researchers found that combining various two-dimensional materials in the same plane or in stacks of layers opens the door to targeting and enhancing specific material properties for applications. The PIs plan to develop computationally efficient models to study and predict the growth and properties of such systems. More specifically, the research will involve determining how defects in these systems alter material properties, as it is well known that defects play a significant role in determining functionality. This research will also involve understanding how defects naturally occur during the growth and manufacturing processes, in order to determine the best methods for producing defect-free structures that would be needed in high-quality material systems and applications.This project supports the training and education of graduate students in cutting-edge materials-physics research and contributes to a globally competitive and diverse workforce through these educational activities. The project will involve broad international collaborations across different scientific disciplines. Outreach activities will be conducted in an all-girls Detroit public school, to provide much-needed enhancement of K-12 science education for female underrepresented minority students.TECHNICAL SUMMARYThis project supports the integration of theoretical and computational research and education to model and predict novel heterostructures and complex defects in two-dimensional (2D) materials and understand underlying fundamental mechanisms. The focus of this research is on the study of both in-plane 2D and out-of-plane quasi-2D heterostructures, nanoscale patterns, and complex topological defects that emerge during the growth and assembly of single- and multi-component 2D materials. Of particular interest are graphene, hexagonal boron nitride, and transition-metal dichalcogenides, among many others. Predictive models, based on the phase-field-crystal method and its amplitude formulation, incorporating both microscopic and mesoscopic scales, will be developed to study the structural and dynamical properties of these fundamentally important nanostructures and defects. These approaches incorporate material elasticity, plasticity, and atomistic details such as dislocations, grain boundaries, and triple junctions on large length and time scales inaccessible to traditional atomistic techniques.The models developed will be used to predict microstructure formation and dynamics of morphologically and compositionally modulated interfacial nanopatterns as well as the formation, motion, and influence of complex defects. Examples include in-plane lateral heterojunctions composed of different types of 2D materials and out-of-plane heterostructures with effects of the third dimension and of deformations. Growth mechanisms will also be investigated to identify the optimal conditions for the controllable synthesis of the predicted nanoscale heterostructures. This research will provide new insights into the fundamental mechanisms governing the development of these low-dimensional material structures, particularly the coupling mechanisms between micro and meso scales and effects of various growth and processing conditions. The study will also enable the investigation and prediction of new thermal and electronic properties of these novel 2D systems, with the goal of linking microstructures to material properties and in turn to processing conditions.This project will contribute to a globally competitive and diverse workforce by training and educating students in cutting-edge research and will involve broad international collaborations across different scientific disciplines. In addition, outreach activities will be conducted to enhance K-12 science education for underrepresented minority students in an all-girls Detroit public school.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.