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Professor Bryan HueyUniversity of ConnecticutHost: Jiamian Hu (MS&E)
3D nanoscale properties of ferroelectrics and photovoltaics via Tomographic AFM
Abstract Nano- Nano- and meso- scale materials properties are crucial to the macroscopic performance of a wide range of functional and photovoltaic devices. Investigations of photoconductivity and ferroelectricity with Atomic Force Microscopy are especially insightful for elucidating the influence of grain boundaries, orientation, strain, 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, concentration, or field gradients. Therefore, we are advancing Tomographic AFM for volumetric materials property mapping, with voxels of properties approaching 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 homogeneous BiFeO3, Tomographic AFM confirms Kay-Dunn thickness scaling (Steffes, PNAS, 2018). The effects on ferroelectric switching due to lateral strain are also accessible (Song, Adv Func Mat, 2021). Finally, co-located domain and current maps directly reveal sub-surface topological defects, and can distinguish few-unit-cell superlattice layers. Such truly volumetric insight into properties is increasingly important for engineering optimal performance and reliability of real-world, 3-dimensional materials devices.
BiographyBryan Huey, Professor and Department Head for MSE at UConn, is 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 2019MRS Fall Meeting, and is the incoming chair of the UMC (association of MSE department heads). 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 3dfluorescence, high speed AFM, and a recent focus on Tomographic AFM.