Heterostructures and Superlattices of Two-Dimensional Layered Materials

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Nontechnical Description: Two-dimensional layered materials represent a new class of material systems for exploring fundamental chemistry and physics at the limit of single-atom thickness, and have the potential to open up completely new technological opportunities beyond the reach of the existing materials, such as high-speed electronics, ultra-flexible electronics, photodetectors, photovoltaics and novel sensors. This project investigates the fundamental nucleation and growth mechanisms of two-dimensional materials and develops synthetic strategies for the growth of these atomically thin crystals with well-defined boundaries in both lateral and vertical directions. The research is closely integrated with education and outreach activities. The project provides students with educational and training opportunities beyond traditional educational boundaries including developing entrepreneurial skills. The materials and methodologies developed in the research are integrated into graduate and undergraduate courses to broaden the educational experience beyond the PI's laboratory.Technical Description: This project aims to design and synthesize two-dimensional layered materials, their heterostructures and superlattices with a precise control of material parameters including chemical composition, physical dimension, number of atomic layers, and heterostructure interfaces. The project uses in-situ transmission electron microscopy to investigate the nucleation and growth kinetics and develops an atomistic understanding of two-dimensional crystal growth within and between atomic layers. The project also develops a laser-assisted chemical vapor deposition approach for programmable switching of chemical precursors to enable the controlled growth of heterostructures with atomically sharp interfaces. The structural, chemical and electronic modulation of the resulting materials is studied using transmission electron microscopy and scanning tunneling microscopy. In addition, the project investigates the fundamental electronic and optical properties of the resulting materials, and explores their applications for novel electronic and optoelectronic devices.