Thesis (Ph.D.)--Wake Forest University. Dept. of Physics, 2003. / Vita. Includes bibliographical references.

Thesis (Ph.D.)--Materials Science and Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Zhong lin Wang; Committee Member: Christopher J. Summers; Committee Member: Kenneth A. Gall; Committee Member: Robert L. Snyder; Committee Member: Russell D. Dupuis.

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Tummala, Rao; Committee Co-Chair: Wang, Zhong Lin; Committee Member: Brand, Oliver; Committee Member: Chang, Gee-Kung; Committee Member: Ghovanloo, Maysam; Committee Member: Wong, Ching-Ping. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1926. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed Sept. 16, 2009). Includes bibliographical references (p. 20-21).

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 97-106).

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references. Also available in electronic version.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 82). Also available in electronic version.

Orientador: José Roberto Ribeiro Bortoleto / Banca: José Humberto da Silva / Banca: Adriana de Oliveira Delgado / O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi / Resumo: Filme finos de AZO foram sintetizados sobre substratos de vidro utilizando um alvo de Zn-Al (5% at Al) com 99,999% de pureza através da técnica RF magnetron sputtering reativo a temperatura ambiente. As propriedades estruturais, elétricas, ópticas e morfológicas foram investigadas em função da variação da pressão de argônio no intervalo de 10 a 50 mTorr. As análises de DXR revelaram que os filmes obtidos são policristalinos come estrutura hexagonal wurtzita e orientação preferencial no plano (002). Além disso, mostrou que o aumento da pressão, reduziu os valores tensão e ocasionou o aumento da presença de vazios entre os grãos. Para todos os filmes finos obtidos as medidas de transmitância óptica apresentaram valores acima de 80% na região visível do espectro entre 500-700 nm. Já os valores de gap óptico decresceram de 3,68 para 3,55 eV com o aumento da pressão. O filme sintetizado a 10 mTorr apresentou os melhores resultados em termos de densidade de portadores e mobilidade elétrica, sendo os valores 2,68 x 10 cm-3/Vs, respectivamente / Abstract: Aluminum zinc oxide (AZO) thin films were synthesized on glass substrates by radiofrequency (RF) magnetron sputtering of a Zn-Al (5at% Al) target of 99.999% purity at ambient temperature. The structural, electrical, optical and morphological properties of the films were investigated as a function of the argon pressure, which was varied from 10 to 50 mTorr. X-ray diffraction (XRD) analyses revealed that the films obtained are polycrystalline with a hexagonal wurtzite structure with a preferential orientation in the (002) plane. In addition, it was show than an increase in pressure reduced the tension and produced an increase in the inter-grain spaces. For all of the films produced optical transmission was above 80% in the visible region (wavelength between 500 nm and 700 nm). As the system pressure was increased the optical gap fell from 3.68 to 3.55 eV. The film synthesized at 10 mTorr presented the best results in terms of the carrier density and electrical mobility, which were 2.68 x 10 cm-3 and 3.0 cm2/Vs, respectively / Mestre

ZnO is an n-type semiconducting material with high optical transparency in the visible range (400 - 750 nm) of the electromagnetic spectrum. When doped with group 13 or 14 metal oxides, ZnO exhibits almost metallic electrical conductivity. ZnO thin films have been recognised as promising alternative material for the currently widely-used but expensive indium oxide in the form of indium tin oxide (ITO), in terms of their low cost and the high abundance of zinc. At the moment, even the best solution-processed ZnO films still can not compete for ITO replacement especially in solar energy utilization and OLED lighting applications, and the performance of ZnO films needs to be further improved. The objective of this work was to enhance the electrical and optical properties of spray pyrolysed ZnO thin films by simultaneous cation and anion doping. This was achieved by growing several series of undoped, single-doped, and co-doped ZnO thin films over a wide range of conditions, in order to understand the growth behaviour of undoped and doped ZnO, and to establish the optimum growth procedure. Spray pyrolysis process has advantages over vacuum-based techniques in terms of its low-cost, high deposition rate, simple procedure and can be applied for the production of large area thin films. Various techniques were employed to characterize the properties of the prepared thin films, and thus determine the optimum growth conditions (i.e. X-ray difiraction (XRD), Xray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), UV-Vis-NIR spectroscopy and Hall effect measurement). The growth of doped ZnO on glass substrates using Si and F as dopants, yielded highly conducting and transparent thin films. The co-doped thin films exhibited distinct widening of band gap upon increasing deposition temperature and doping concentration as a result of increasing electron concentration up to 4.8 x 10²⁰ cm^-3 upon doping with Si and F at the same time. The resistivity of the films deposited from Zn(acac)₂ · xH₂O solutions and at the optimum temperature of 450 °C, was found to decrease from 4.6 x 10^-2 Ωcm for the best undoped ZnO film to 3.7 x 10^-3 Ωcm, upon doping with 3% Si. The films co-doped with Si and F in the ratios of [Si] / [Zn]= 3 - 4 mol% and [F] / [Zn]=30 - 40 mol% were the most conducting (p ∼ 2.0 x 10^-3 Ωcm). The associated optical transmittance of co-doped ZnO was above 85% in the whole visible range. Results compare favourably with In-doped ZnO deposited under similar conditions. Si+F co-doped ZnO films offer a suitable replacement for ITO in many applications such as LCD and touch screen displays.

Made available in DSpace on 2015-03-03T11:52:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-16Bitstream added on 2015-03-03T12:07:24Z : No. of bitstreams: 1 000806683.pdf: 1193891 bytes, checksum: 1226deee936f356b44515bf10a7e5739 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Filme finos de AZO foram sintetizados sobre substratos de vidro utilizando um alvo de Zn-Al (5% at Al) com 99,999% de pureza através da técnica RF magnetron sputtering reativo a temperatura ambiente. As propriedades estruturais, elétricas, ópticas e morfológicas foram investigadas em função da variação da pressão de argônio no intervalo de 10 a 50 mTorr. As análises de DXR revelaram que os filmes obtidos são policristalinos come estrutura hexagonal wurtzita e orientação preferencial no plano (002). Além disso, mostrou que o aumento da pressão, reduziu os valores tensão e ocasionou o aumento da presença de vazios entre os grãos. Para todos os filmes finos obtidos as medidas de transmitância óptica apresentaram valores acima de 80% na região visível do espectro entre 500-700 nm. Já os valores de gap óptico decresceram de 3,68 para 3,55 eV com o aumento da pressão. O filme sintetizado a 10 mTorr apresentou os melhores resultados em termos de densidade de portadores e mobilidade elétrica, sendo os valores 2,68 x 10 cm-3/Vs, respectivamente / Aluminum zinc oxide (AZO) thin films were synthesized on glass substrates by radiofrequency (RF) magnetron sputtering of a Zn-Al (5at% Al) target of 99.999% purity at ambient temperature. The structural, electrical, optical and morphological properties of the films were investigated as a function of the argon pressure, which was varied from 10 to 50 mTorr. X-ray diffraction (XRD) analyses revealed that the films obtained are polycrystalline with a hexagonal wurtzite structure with a preferential orientation in the (002) plane. In addition, it was show than an increase in pressure reduced the tension and produced an increase in the inter-grain spaces. For all of the films produced optical transmission was above 80% in the visible region (wavelength between 500 nm and 700 nm). As the system pressure was increased the optical gap fell from 3.68 to 3.55 eV. The film synthesized at 10 mTorr presented the best results in terms of the carrier density and electrical mobility, which were 2.68 x 10 cm-3 and 3.0 cm2/Vs, respectively