Near Field Enhanced Raman Spectroscopy - Applications to Ferroelectric Thin Films

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This Small Grants for Exploratory Research (SGER) award will support a project investigating the application of near-field enhanced micro-Raman Spectroscopy to ferroelectric thin films. Micro-Raman spectroscopy has been shown to be a useful tool for material characterization. However, in transparent ferroelectric thin films grown on insulating substrates the Raman signal drops to undetectable levels. In some materials the Raman signal can be enhanced through the use of the surface enhanced Raman scattering effect (SERS). An attempt will be made to create SERS conditions in thin ferroelectric films of interest by introducing metallic (Au) nano-particles at the surface, the substrate interface, or within the bulk of the films. A second method will employ a gold plated atomic force microscope (AFM) tip to act as a single metallic particle placed on the back side of a transparent substrate. This second method will also be explored as a way to map out, on the nano-scale, properties of extended ferroelectric thin films.%%%Ferroelectric materials play a great role in many technological applications. The next generation of advanced and compact integrated electronics will require thin films of new classes of complex electroceramic and other optoelectronic materials. Recent developments in material processing and thin film fabrication techniques have made available high quality thin films suitable for these applications. Ferroelectrics are a class of electroceramics that offer a wide range of useful properties that could be used to develop devices, such as smart sensors and structures, radiation-hard non-volatile computer memories, and pyroelectric detectors. Successful implementation of these devices will require materials with well-defined properties and device figures of merit. Micro-Raman spectroscopy has emerged as an excellent non-destructive tool for comprehensive materials characterization by investigating the effects of size, stress/strain, temperature, pressure, and electric field on the dynamic scattering behavior. To obtain Raman signals of measurable strength from thin films, it is necessary to enhance the electric field strength of the exciting radiation. The method of surface enhanced Raman scattering (SERS) has proven to be extremely successful in applications to macroscopic systems. The present exploratory research will investigate methods of applying the SERS process to characterize ferroelectric thin films in the nano-domain..***