Optical and Electrical Properties of Composite Nanostructured Materials
AuthorAmooali Khosroabadi, Akram
Transparent Conducting Oxide
AdvisorNorwood, Robert A.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractA novel lithographic fabrication method is used to fabricate nanopillars arrays of anisotropic Ag and TCO electrodes. Optical and electrical properties of the electrodes including bandgap, free carrier concentration, resistivity and surface plasmon frequency of different electrodes can be tuned by adjusting the dimensions and geometry of the pillars. Given the ability to tune the nonlocal responses of the plasmonic field enhancements, we attempt to determine the nature of the effective refractive index profile within the visible wavelength region for multi-layer hybrid nanostructures. Knowledge of the effective optical constants of the obtained structure is critical for various applications. nanopillars of TCO\Ag core shell structures have been successfully fabricated. The Maxwell-Garnett mixing law has been used to determine the optical constants of the nanostructure based on spectroscopic ellipsometry measurements. Simulated reflection spectra indicate a down shift in the Brewster angle of the pillars resulting from the reduction in the effective refractive index of the nanostructure. Two plasmonic resonances were observed, with one in the visible region and the other in the IR region. Plasmon hybridization model is used to describe the behavior of metal and metal oxide core shell nanostructured electrodes. Different charge density distributions around the pillars determine the plasma frequency which depends on the core and surrounding media dielectric constants. Finite Difference Time Domain (FDTD) simulation of different structures agree well with experiment and help us to understand electric field behavior at different structures with different geometries and dielectric constants. Plasmonic Ag nanopillar arrays are effective substrates for surface enhanced Raman spectroscopy (SERS). An enhancement factor up to 6 orders of magnitude is obtained. Monolayers of C60 is deposited on the Ag nanopillars and the interface of C60/Ag is studied which is important in optoelectronic devices. Electron delocalization between C60 and Ag is confirmed.
Degree ProgramGraduate College