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

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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.