CAREER: Bicrystallography-informed Mechanics of Two-dimensional Heterointerfaces

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

This Faculty Early Career Development (CAREER) award will support research to explore how strain can be used to study the structural response of heterointerfaces for the design and synthesis of atomically thin two-dimensional materials systems. Heterostructures formed by stacking distinct two-dimensional materials demonstrate exceptional mechanical and electronic properties, such as superlubricity, high strain tolerance, and correlated electronic physics. These properties originate from the van der Waals interactions at the heterointerfaces formed by the two-dimensional materials. A fundamental feature that dictates the structural response of a heterointerface is the degree of incommensurability or incompatibility between the atomic lattices that form it. However, the problem of quantifying incommensurability and its effect on the structural response remains a fundamental open question, which will be explored in this project. The success of this study will lead to a theoretical and computational framework to strain engineer two-dimensional materials systems for applications such as next generation nanolubricants and electronic and optoelectronic devices. On the education and outreach front, the project will develop transdisciplinary STEAM activities wherein Art and Science complement each other. These activities will involve working directly with undergraduate and high school students and collaborating with high school teachers to develop learning modules centered around the science and art behind overlapping two-dimensional atomic lattices. The dominant influence of bicrystallography on the design, synthesis, and transfer of two-dimensional materials systems and the ability to control the local microstructure using strain applied at the macroscale motivate this project's goal: to realize the full potential of strain engineering as a route to modulate the atomic reconstruction in heterointerfaces for functional performance gains. The objective is to completely characterize the response of heterointerfaces to temperature and shear and normal forces in terms of the interface's microstructure. This study will develop a unified framework wherein bicrystallography takes center stage to explore how a structural response to incommensurability manifests in interfacial dislocation behavior. Bicrystallography will be examined using algebraic tools like the Smith normal form to reveal the translational symmetry of the heterointerfaces and characterize their interface dislocations. Strain and substrate engineering will be realized by the modeling of interface dislocations and substrate lattice steps at the continuum and mesoscale. The outcome will lead to a new understanding of how structural properties emerge from van der Waals interactions and pave the way for a systematic design and large-scale synthesis of heterostructures. 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.