"Effect of Film Thickness on CeO2/Au Vertically Aligned Nanocomposite Morphology and Properties" 

Matteo Moceri, MSE PhD Candidate 

Advisor: Professor Haiyan Wang

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ABSTRACT

The primary goal of this study was to form a general picture of how growth conditions affect the morphology and crystallography of CeO2/Au vertically aligned nanocomposite (VAN) thin films. Additional focus was placed on how any changes in morphology and crystallography translate to tunable optical properties. The morphological effects were observed and analyzed via two main approaches: the change in morphology was observed at multiple points along a given film’s thickness, and the morphology at the film/substrate interface was analyzed with respect to total film thickness. The changes in Au crystallography were observed by measuring peak shift in XRD patterns and determining the resulting in- and out-of-plane strain. To observe additional effects of this morphology change, optical measurements were taken for films at the bottom, middle, and top of the thickness range. Strong trends in transmittance, plasmonic absorption peak shifts and hyperbolic permittivity behavior were all observed with respect to changing thickness. This tunability of optical properties likely arises from changes in both Au pillar phase morphology and crystallography. These findings demonstrate that changing film thickness may be a desirable method to easily tune the optical properties of VAN thin films.