

@mastersthesis {6226,
	title = {Electrical and optical properties of silica based nanostructures and their applications},
	year = {2005},
	note = {3201666},
	school = {The University of New Mexico},
	type = {phdPh.{D}.},
	address = {Ann Arbor},
	abstract = {Despite recent advances in the synthesis and characterization of nanocrystal (NC) arrays, numerous challenges remain limiting their practical applications. It is the aim of our work to further the understanding of both the synthesis and electrical \& optical properties of gold NC/silica arrays possessing both chemical and thermal stability. The gold NC/silica films are fabricated through self-assembly of water-soluble gold nanocrystal micelles and soluble silica by sol-gel processing. Metal-NC/oxide-semiconductor capacitor samples exhibit charge storage with discharge behavior dominated by electron transport within the gold NC arrays. Low temperature current-voltage measurements on metal-insulator-metal devices reveal electrical conduction with a thermal activation energy of \~{}90 meV. For temperatures less than 100 K, the I-V characteristics of the NC film exhibits a strong coulomb blockade effect, with a threshold voltage of \~{}0.5 V measured at 78 K. The observed scaling behavior of the I-V characteristics at low temperature is consistent with a 3-D NC film. These results on carrier transport are the 1st performed on highly ordered 3-D NC arrays. Surface plasmon resonance (SPR) was investigated for the gold NC/silica films using a prism coupler. The absorption spectra show a strong SPR absorption at \~{}520 nm. The angular excitation spectra show a steep dip in the reflectivity curve at \~{}65{\textdegree} depending on the thickness and refractive index of the gold NC/silica film. The corresponding angular spectra of films with different gold loading factors were also measured and compared with the modeling results. Collective optical behavior is observed for the 3-D ordered gold NC arrays, and resulted in a blue shift in the plasmon absorption peak with increasing gold loading. Gold nanoparticle composite materials are known to display large optical nonlinearities and rapid time response in SPR region. We evaluated the third order nonlinear optical susceptibility for these films using the z-scan method, and an absolute value, {\textbar}χ (3) {\textbar}, of \~{}1.1 {\texttimes} 10-7 esu was obtained as a result of enhanced local field near SPR frequency.},
	keywords = {0544:Electrical engineering, 0794:Materials science, Applied sciences, Electrical engineering, Gold, Materials science, Nanocrystals, Silica films, Sol-gel},
	url = {http://search.proquest.com/docview/305466155?accountid=14270},
	author = {Yang, Kai}
}
