Collaborative Research: Revealing the Role of Structural Modulations on the Electronic Properties of Hexagonal Chalcogenide Perovskite Semiconductors

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NON-TECHNICAL DESCRIPTION: Chalcogenides that contain sulfur, selenium, and tellurium are functional semiconductors with broad applications in information storage and processing, and in energy conversion. A subset of these materials with hexagonal symmetry demonstrate strong light-matter interactions with potential applications in sensing and communication. This project employs an integrated theoretical and experimental approach to establish axioms elucidating the role of subtle changes in composition and structure in these materials on electronic properties, and to achieve desired properties such as optical anisotropy by controlling composition and structure. Graduate students are being trained to use a mix of theory and experiments to address fundamental problems in materials science and engineering. Education activities focus on preparing graduate and undergraduate students for a workforce needed to realize advanced energy and information technologies. TECHNICAL DETAILS: The project seeks to unravel the role of non-stoichiometry and structural modulations on the electronic structure of hexagonal chalcogenides perovskites, and control their physical properties including optical anisotropy and electronic transitions, by changing their composition and structure. The research employs vapor-transport single crystal growth and pulsed laser deposition to grow chalcogenide perovskites. A combination of x-ray, neutron, and electron-based probes are used to characterize structure and composition at multiple length scales. Physical properties are characterized using optical spectroscopy and electrical transport studies. First-principles electronic structure calculations are used to establish atomic origins of the experimentally observed properties. Education aspects include training of graduate and undergraduate students to use an integrated theoretical and experimental approach to investigate and design materials. This project supports the development of course modules on atomic-scale modeling and atom-by-atom growth of functional materials, and the organization of symposia at national meetings on functional semiconductors and chalcogenide perovskites.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.