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MSE Seminar: “Nano-Volumetric Materials Properties of Ferroelectrics and Photovoltaics via Tomographic AFM”
November 12, 2020 at 10:45 AM - 11:45 AM
Nano- and meso- scale materials properties are crucial to the macroscopic performance of a wide range of functional and photovoltaic devices. In 2-dimensions, photoconductivity, ferroelectricity, and even domain dynamics have thus been investigated for decades now especially using variations of Atomic Force Microscopy. Our work and others reveals how these properties are frequently mediated by strain, orientation, grain boundaries, and other microstructural defects or heterogeneities. However, practical devices are often sensitive to, or even controlled by, sub-surface effects or thickness dependencies related to microstructure and concentration, polarization, and/or field gradients. Therefore, we are advancing Tomographic AFM for volumetric materials property mapping, with voxels of properties on the order of ~10 nm3. With polycrystalline photovoltaics such as MAPbI3 and CdTe, TAFM literally uncovers new pathways to improve carrier separation via inter- and intra- granular defects (Luria, Nature Energy, 2017; Song, Nature Communications, 2020). For BiFeO3, Tomographic AFM confirms Kay-Dunn thickness scaling, LGD behavior with a minimum switchable thickness of <5 nm, and even co-located domain and current maps which together directly reveal sub-surface topological defects (Steffes, PNAS, 2018). Such volumetric insight is increasingly important for engineering optimal performance and reliability of real-world, 3-Dimensional materials devices.
Bryan Huey, University of Connecticut
Department Head and Professor of Materials Science and Engineering
Bryan Huey is a Professor and the Department Head of Materials Science and Engineering at the University of Connecticut. Bryan is a UPenn MSE PhD alum (’99, Bonnell group), the past chair of the 1200 person Basic Science Division of the American Ceramic Society, was one of five overall organizers for the 7000 attendee 2019 MRS Fall Meeting, and co-organizer for previous EMA and US-Japan conferences. He is an expert in the development and application of advanced variations of Atomic Force Microscopy for studying piezoelectrics, multiferroics, photovoltaics, MEMS, and biological cells and tissue. This includes simultaneous AFM and 3d fluorescence, high speed AFM, and Tomographic AFM.