Ferroelectric materials are found in countless, widespread applications, e.g.: as barcode readers in grocery checkouts and as the devices that make today's Internet possible. Many of these applications exploit the ability to reduce the size of the relevant device features to micron dimensions and to tailor properties of the material by properly arranging ferroelectric domains. However, existing devices are based on bulk crystals or wafers with thicknesses of 0.5 mm or more. This limits the ability to produce devices that are more compact in size or are easily tunable in their function. This work aims at developing the materials foundations for new platforms with reduced dimensionality to overcome these limitations. The PI of this Materials World Network grant collaborates with two groups in Germany (Prof. Karsten Buse, University of Bonn and Prof. Detlef Kip, Helmut Schmidt University Hamburg) which are supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation). Through this international program, undergraduate, graduate and post-doctoral scholars acquire a unique perspective in interacting globally through travel exchanges and workshops involving all participating organizations. Undergraduate research and exchange is a strong element of this collaboration involving Lehigh's undergraduate students and targeting especially underrepresented students. The team also contributes to the Lehigh Science Outreach program by organizing annual outreach workshops for high school students
TECHNICAL DETAILS: The project focuses on the development of two novel material platforms: (1) The lithium-niobate-on-insulator platform (LNOI) utilizing 3 inch wafer-sized crystal slices and photonic wires with optical confinement below 1 micron. (2) Single domain nanocrystals in sizes between 10-100 nm. The multifaceted approach of the team spans from solving basic science questions about the changes in bulk properties due to the reduced dimensionality and the increased role of surfaces and interfaces, to the development of specially adapted methods for domain patterning and the alignment of ferroelectric nanoparticles, to the demonstration of devices such as a cw-THz source and other nonlinear frequency converters. The team exploits its expertise in the fabrication of wafer-scale lithium-niobate-on-silicon-oxide as well as in preparation of mono-disperse lithium niobate nanocrystals and will utilize surface sensitive characterization methods such as near-field UV-Raman spectroscopy, high-resolution transmission electron microscopy and low energy ion scattering. The possibility of manipulating the orientation of nanocrystals will be studied in a novel optical tweezers instrument, which allows 3D control of light polarization and in situ Raman characterization.
