As restaurações monolíticas de Y-TZP (Zircônia Tetragonal Policristalina estabilizada por Itria) se apresentam como uma alternativa interessante devido a suas elevadas propriedades mecânicas, porém existe a preocupação quanto a Degradação em Baixa Temperatura (DBT). Os compósitos ZTA (Alumina reforçada por Zircônia) tem o potencial de atender a esta demanda, apesar do desafio estético uma vez que a passagem de luz pode ser limitada pela combinação de duas fases cristalinas. O presente trabalho teve como objetivo inovar na criação de um compósito ZTA sintetizado com Y-TZP translúcida, na procura de um material com alta resistência mecânica em relação à alumina, resistente à DBT quando comparada à YTZP e com propriedades ópticas melhoradas em relação ao ZTA sintetizado com Y-TZP convencional. Sessenta corpos de prova (discos de 12 mm de diâmetro por 1 mm de espessura) foram confeccionados e divididos em quatro grupos: zircônia convencional (3YSB-E), zircônia translucida (Zpex), compósito ZTA (Al2O3-70%v ZrO2-30%) sintetizado com 3YSB-E (ZTA-3YSB-E) e outro com zircônia translucida Zpex (ZTA-Zpex). Os corpos de prova foram obtidos mediante prensagem uniaxial e isostática dos pós cerâmicos. Após sinterização, o polimento das duas faces foi realizado com discos e suspensões diamantadas de até 1 m. A caracterização óptica foi realizada mediante testes de refletância sobre fundo branco e preto para determinar a razão de contraste (RC) e o parâmetro de translucidez (PT) mediante a diferença de cor (E). Difração de Raios-X (DRX) e Microscopia Eletrônica de Varredura (MEV) foram realizadas para estudo da microestrutura do material. Análise de variância ANOVA e teste de Tukey com nível global de significância de 5% foram utilizados na análises dos dados de propriedades ópticas. A RC mostrou opacidade significativamente menor para o grupo Zpex (0.77; p=0.0001), o grupo 3YSB-E mostrou valores intermediários (0.84; p=0.0001), sendo que os dois compósitos ZTA apresentaram valores maiores de opacidade (ZTA-3YSB-E = 0.99 e ZTA-Zpex = 1) sem diferença significante entre eles (p=0.7433). Para o PT os compósitos ZTA mostraram um E baixo (ZTA-Zpex = 0.22 e ZTA-3YSB-E = 0.43), sem diferença significante entre os grupos (p=0.5). O grupo 3YSB-E apresentou valores intermediários e significativamente diferentes em relação aos outros grupos (E = 7.11 p<0.0001). Já o grupo Zpex apresentou a menor capacidade de mascaramento com E =10.19 (p<0.0001). A DRX mostrou similaridade das fases cristalinas dos grupos 3YSB-E e ZPEX evidenciando que as mesmas foram preservadas na mistura nos compósitos, sem mostrar alterações da estrutura cristalina. A analise no MEV em até 1.500x de aumento evidenciou pouca alteração morfológica entre as zircônias e entre os ZTAs. As propriedades ópticas do ZTA Zpex não foram estatisticamente diferentes do compósito sintetizado com 3YSB-E, sendo que as Y-TZPs apresentaram menor opacidade. As Y-TZPs mostraram estrutura cristalina regular sem a formação de aglomerados e os compósitos ZTAs apresentaram uma mistura uniforme, mantendo as características da estrutura cristalina tanto da Y-TZP quanto da Al2O3, sem formação de aglomerados nem segregação dos grãos dos compósitos. Novos estudos são necessários para avaliar a resistência a DBT e as propriedades mecânicas destes materiais experimentais. / Monolithic Yttria stabilized Tetragonal Zirconia Polycrystals (Y-TZP) prostheses are considered an interesting treatment alternative due to their high mechanical properties. Nevertheless there is concern about the Low Temperature Degradation (LTD) process. Zirconia-Toughened Alumina (ZTA) composites seem to be capable of meeting this demand, while facing the challenge of being aesthetically suitable, since the passage of light can be limited by the combination of two polycrystalline phases. The present work aimed to innovate in the synthesis of a ZTA composite with a translucent Y-TZP for dental applications, in the search for a material with high mechanical resistance when compared to alumina, resistant to LTD when compared to Y TZP, and with improved optical properties over ZTA synthesized with conventional Y-TZP. Sixty disc shaped specimens with 12 mm diameter and 1 mm thick, were prepared and divided in four groups: a conventional zirconia (3YSB-E), a translucent zirconia (Zpex), a ZTA composite (Al2O3-70%v ZrO2-30%) synthetized with 3YSB-E (ZTA- 3YSB-E), and a ZTA composite synthetized with translucent zirconia (ZTA-Zpex). The specimens were obtained by uniaxial and isostatic pressing of the ceramic powders. After sintering, polishing of both sides was performed with diamond disks and suspensions up to 1 m. The optical characterization was performed by means of reflectance on a white and a black background to determine the contrast ratio (CR) and the translucency parameter (TP) of the experimental groups. XRD and SEM analyses were performed to study the crystalline structure. Analysis of variance ANOVA and Tukey test with a global significance level of 0.05% were used to analyze the data. CR showed significantly lower opacity for Zpex group (0.77, p = 0.0001), 3YSB-E showed intermediate values of opacity (0.84, p = 0.0001), and both ZTA composites presented higher opacity (ZTA-3YSB-E = 0.99 and ZTA-Zpex = 1) with no statistically significant difference between them (p = 0.7433). The TP showed a low E for ZTA composites (ZTA-Zpex = 0.22 and ZTA-3YSB-E = 0.43), with no statistically difference between the groups (p = 0.5). The 3YSB-E group presented intermediate and significantly different values of TP relative to the other groups (E = 7.11 p <0.0001). The Zpex group presented the lowest masking ability with E = 10.19, also significantly different from the other groups (p <0.0001). The XRD showed similarity of the crystalline phases of 3YSB-E and ZPEX, structure that were preserved in the blends in ZTA composites, without showing changes in the crystalline structure of the materials. SEM analysis (up to 1.500 x) showed low morphologic alteration between Y-TZP and ZTA composites. Optical properties of ZTA-Zpex showed no statistical difference when compared with ZTA-3YSB-E, whereas Y-TZP groups showed less opacity than other groups. The experimental Y-TZPs showed a regular crystalline structure without the formation of agglomerates, and the ZTA composites presented a uniform mixture of the phases, maintaining the characteristics of the polycrystalline structure of both Y-TZPs and Al2O3, without the formation of agglomerates or segregation of the grains in the composites. Future tests evaluating the resistance to LTD and mechanical properties of these experimental materials are warranted.

Part I focuses on studying the extent of cooperation in networked entities, within the context of the Prisoner's Dilemma (PD) and the Snowdrift Game (SG). The iterated prisoner's dilemma (IPD) is studied in the full payoff space spanned by two parameters beta and gamma. A theoretical study on two-strategy IPD is presented. We then numerically study the IPD in the full payoff space, with four different initial configurations. It is found that including the Tit-for-tat-like (ETFT) and Always-defecting-like (EAllD) strategies as initial strategies can maximize the dominating area of generous strategies in the payoff space at equilibrium. The roles played by ETFT and EAllD are further studied on the diagonal and anti-diagonal lines of the payoff space. / Part II focuses mainly on studying the optical properties of grating within the Rigorous Coupled-Wave Analysis (RCWA) method. The surface plasmon (SP) dispersion relation in a system consisting of a thin metallic film sandwiched between a linear dielectric and nonlinear dielectric of arbitrary non- linearity is derived, based on a generalized "first integral" approach. The SP dispersion relation in a system consisting of a thin metallic film sandwiched in a symmetric nonlinear dielectric environment is then derived. The changes in SP dispersion relations on film thicknesses are discussed for both cases. / The optical properties of two samples of one-dimensional metallic reflection gratings are studied. The numerical results of the zeroth order reflectance are in good agreement with experimental data. The Wood's anomaly occurs when a particular diffraction order emerges or disappears, thus inducing a change in the efficiency of other diffraction orders. This phenomenon is studied by calculating and measuring the efficiencies of all allowed diffraction orders. Numerical results of the near field patterns show a coupling between the waveguide and SP modes. We also study the controllable enhanced trans- mission in a semiconductor grating. The dielectric constant of a semiconductor becomes a tensor in the presence of a static magnetic field parallel to the slit. Numerical results based on RCWA reveal that the zeroth order transmission peaks at normal incidence can be shifted to longer wavelengths and the peak values of transmission can largely be enhanced when a moderate magnetic field is applied. A single-mode theory incorporating anisotropy is developed. The analytic results are in quantitative agreement with RCWA, indicating that the tunability in the transmission stems from the waveguide mode. / The Snowdrift Game is regarded as an important alternative to PD in studying the emergence of cooperation in competing populations. The phase transitions in spatial snowdrift games are introduced. By studying the relative alignments of the payoffs of C and D nodes, the phase transitions are analytically explained. As an extension to the standard two-person SG, an N-person Snowdrift Game (NPSG) is proposed to include generic multi-person interactions. NPSG in a well-mixed population is studied analytically by using the replicator dynamics. A simulation algorithm is developed. We also study NPSG on lattices and find a suppressed cooperation frequency, when compared with the well-mixed case. For NPSG played on 1D chain, the problem can be solved analytically. We further extend our work to study co-evolving dynamics. We propose and study a model in which the connections are driven to evolve by the dynamics of SG. Compared with played on static network, the cooperation frequency is promoted. A semi-analytic theory is proposed, with the results qualitatively agree with simulation results. / The thesis consists of two independent parts. Part I focuses on evolutionary games in networked entities and Part II focuses on calculations on optical properties of metallic gratings. / Yin, Haiping = 競爭群體中合作的產生及具規則結構之金屬薄膜的光學性質 / 尹海平. / Adviser: Hui Pak Ming. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 185-200). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Yin, Haiping = Jing zheng qun ti zhong he zuo de chan sheng ji ju gui ze jie gou zhi jin shu bo mo de guang xue xing zhi / Yin Haiping.

As another important features in VEELS, the plasmon excitations (including the volume plasmon and surface/interfacial plasmon) are also utilized to identify different phases and multi compositions within materials. The microstructure and electronic structure evolution of silicon-rich oxide (SRO) films as a function of the annealing temperature are investigated using TEM and VEELS. The as-deposited SiO film is found to be a single phase with only single volume plasmon presents in VEEL spectrum and almost no interfacial plasmon is observed. After the annealing (Tanneal>400&deg;C), it begins to decomposite into Si and SiO2 and the single phase changed into cluster/matrix nanocomposites where the interfacial plasmon appears. The Si duster size and its concentration increase as the annealing temperature increases. / Firstly, the applications of VEELS in investigating the electronic structures of ZnO nanowires with different diameter and surface shapes are demonstrated. Using the momentum transferred technique, one of the interband transitions with dipole-forbidden nature is identified. Several size dependent features are found on the interband transitions and plasmon oscillations of ZnO nanowires with small diameter and circular cross section, which are mainly due to the large surface to volume ratio and existence of Oxygen dangling bonds on those ZnO wires. / Further explorations on the electronic structure in the vicinity of band gap are carried out for the ZnO nanowires doped with different dopants (Co, Er, Yb) and different dopant concentrations. In order to obtain trustworthy information in the very low energy range of VEELS a narrow zero loss peak and elimination of Cerenkov effect and surface losses are necessary, which can be realized by incorporation of the gun monochromator in the TEM and taking spectrum at a momentum transfer slightly greater than zero. Band tail states (&sim;2-3.3 eV) are found to be generated in the ZnO nanowires after the ion implantation and their density of states increase with the ion fluence increases. The partially removal of those defect states by the Oxygen annealing is also observed in VEELS. On the other hand, interesting mid-gap state(s), which is dopant-sensitive (as it is only observed in the rare earth (Er and Yb) doped ZnO nanowires, but not in the Co-doped ones), does not show obvious change after the O annealing. The impact of these electronic structure changes on the material properties are also discussed. / In the end of the thesis, some of the practical limitations and contradictories on the energy resolution (DeltaE), spatial resolution (Delta x), and the momentum resolution (Deltaq) when carrying out the various VEELS study are summarized. The compromise made among these resolution limits is also discussed. / In this work, the important experimental parameters and appropriate data processing methods to generate trustworthy data are discussed. Based on that, three material systems, i.e., pure ZnO nanowires, doped ZnO nanowires, and Si/SiO/SiO2 composite films are investigated. Various information on the material microstructure/electronic structure is interpreted using the VEELS data. / The valence-electron energy-loss spectroscopy (VEELS) contains information on the electronic structures of materials, including the band gap the single-electron interband transitions and the plasmon oscillations. When operating in transmission electron microscope (TEM), the excellent spatial resolution enables the VEELS not only exploring the local electronic structures of individual low dimensional nanostructured materials, but also building up correlations between the electronic structure and microstructure. In addition, the capability in carrying out the momentum transfer dependent study in VEELS allows the investigation on the dispersion of plasmons and single electron excitations in the momentum space. The optically forbidden transitions, which are not allowed in conventional optical method, can also be excited at high momentum transfer values using VEELS. / Wang, Juan = 價電子能量損失譜在低維納米材料中的應用 / 王娟. / "September 2007." / Adviser: Li Quan. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1267. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 122-133). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307. / Wang, Juan = Jia dian zi neng liang sun shi pu zai di wei na mi cai liao zhong de ying yong / Wang Juan.

This thesis explores the design, synthesis and characterisation of iridium(III) complexes for optoelectronic applications; in particular, cationic [Ir(CˆN)₂(NˆN)]⁺-type emitters (where CˆN is an anionic bidentate cyclometalating ligand such as 2-phenylpyridinato, ppy, and NˆN is a neutral bidentate ligand such as 2,2'-bipyridine, bpy) for use in light-emitting electrochemical cells (LEECs). Design strategies aim to achieve high photoluminescence quantum yields (Φ[sub](PL)) for these complexes. Chapter 1 provides an overview of the fundamental photophysics of luminescent transition metal complexes, before reviewing state of the art iridium complexes employed in LEEC devices. Chapter 2 employs a combination of the electron-deficient 2,4-difluorophenylpyridine (dFppy) CˆN ligand and various functionalised biimidazole (biim) NˆN ligands. Within the family of different biim ligands the emission energy does not vary significantly, but the excited state kinetics di.er depending on the rigidity of the biim ligand. Combining the lead biim ligand with a sterically bulkier CˆN ligand gives an iridium complex that emits deep blue light with 90% Φ[sub](PL) in MeCN. Chapter 3 describes an approach to replacing the electrochemically unstable aryl carbon-fluorine bonds in dFppy, while maintaining the deep blue emission colour observed for the complexes in Chapter 2. Chapter 4 expands on the concept of rigid biim ligands to bibenzimidazoles (bibenz). Combining conjugated bibenz NˆN ligands with more conjugated CˆN ligands allows for the emission colour of these complexes to be tuned to the orange/red. The Φ[sub](PL) necessarily falls due to the energy gap law, but is nevertheless higher than values measured for reference complexes. Chapter 5 explores the use of an arylazoimidazole ligand with donor-acceptor intraligand charge transfer characteristics in order to red-shift the emission further. The resultant complex is poorly emissive, but shows a panchromic absorption profile and high molar absorptivity, which is unusual for iridium(III) complexes. The absorption profile can be tuned as a function of the protonation state of the imidazole.

L'innovation de la technologie de pointe et l'exigence du marché électronique se concentrent toujours sur l'électronique bon marché, qui présente une fabrication facile, avec des performances sans cesse améliorées. Les pérovskites hybrides organiques-inorganiques, qui combinent les propriétés des semi-conducteurs organiques et inorganiques, sont des candidats prometteurs pour de futurs dispositifs opto-électroniques. L’énergie de liaison des excitons et la force d'oscillateur sont très élevées dans ces systèmes, ce qui rend possible leurs applications à température ambiante. Dans cette thèse, nous avons étudié des couches minces auto-assemblées de molécules de pérovskite (R-NH3)2PbX4. En modifiant la structure R, des pérovskites avec des propriétés optimisées (propriétés optiques d’émission, rugosité de surface et photostabilité) ont été découvertes. Nous avons aussi développé des méthodes pour fabriquer des cristaux massifs et des nanoparticules de pérovskites, et nous avons créé de nouveaux cristaux de pérovskite mixtes: (RNH3)2PbYxX4-x et AB-(NH3)2PbX4. Des cavités verticales en régime de couplage fort ont été réalisées avec ces matériaux, l’émission du polariton de basse énergie a été observée à température ambiante. / The innovation of advanced technology and the requirement of electronic market are always focusing on low cost electronics, presenting an easy processing and having enhanced performance. Organic-inorganic hybrid perovskites, which combine the properties of organic and inorganic semiconductors, are hopeful candidates for future opto-electronic devices. The exciton binding energies and oscillator strengths are very large in these systems making the applications at room temperature possible. In this thesis, we study the flexibility and photostability of self-assembled two-dimensional layered perovskites (R-NH3)2PbX4. By modifying the R structure, perovskites with optimized photoluminescence efficiency, surface roughness and photostability are discovered. We develop also some methodologies to fabricate crystal bulks and nanoparticles of perovskites, and we create new mixed perovskite crystals: (RNH3)2PbYxX4-x and AB-(NH3)2PbX4. Vertical microcavities containing these new materials and working in the strong coupling regime at room temperature have been realized, the emission of the lower energy polariton is observed.

Lo, Ming Gai Stanley. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 131-135). / Abstracts in English and Chinese. / Title Page --- p.i / Abstract --- p.ii / Acknowledgements --- p.v / Table of Contents --- p.vii / List of Figures --- p.ix / List of Tabic --- p.xiv / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Photonic Integrated Circuits --- p.1 / Chapter 1.2 --- Silicon Photonics --- p.7 / Chapter 1.3 --- Optical Modulators --- p.15 / Chapter 1.4 --- Modulation Mechanisms in Silicon --- p.19 / Chapter 1.5 --- Motivation --- p.27 / Chapter 1.6 --- Thesis Outline --- p.28 / Chapter Chapter 2: --- Use of Silicon-bascd Modulators in Radio-over-fiber Optical Links --- p.29 / Chapter 2.1 --- Modeling of Linearity of Silicon Carrier Depletion-based Modulators --- p.31 / Chapter 2.2 --- Modeling of Dependence of Linearity on Various Diode Structures --- p.45 / Chapter 2.3 --- Experiment of Radio-over-Fiber Signal Transmission by a Carrier-Injection Silicon Microring Modulator --- p.52 / Chapter 2.3.1 --- Device Fabrication --- p.53 / Chapter 2.3.2 --- Experimental Setups --- p.59 / Chapter 2.3.3 --- Experimental Results --- p.61 / Chapter 2.4 --- Summary --- p.66 / Chapter Chapter 3: --- Novel Diode Structures and T-Rail Travelling-Wave Electrodes to Enhance the Performance of Depletion-based Modulators --- p.67 / Chapter 3.1 --- Requirements of Diode Design for Depletion-based Optical Modulators --- p.70 / Chapter 3.2 --- Diode Design Principle --- p.72 / Chapter 3.3 --- Modeling Results of Vertical-Junction p-n Diodes --- p.79 / Chapter 3.4 --- Fabrication Process of the Silicon Modulator --- p.88 / Chapter 3.5 --- Experimental Results of the Fabricated Devices --- p.92 / Chapter 3.6 --- T-Rail Travelling-Wave Electrodes --- p.102 / Chapter 3.6.1 --- The Limiting Factors to the Speed of Depletion-based Modulators --- p.102 / Chapter 3.6.2 --- The Design Principle of T-Rail Travelling-Wave Electrodes --- p.104 / Chapter 3.6.3 --- The Fabricated Devices --- p.111 / Chapter 3.7 --- Summary --- p.112 / Chapter Chapter 4: --- Conclusion and Future Work --- p.113 / Chapter 4.1 --- Conclusion --- p.113 / Chapter 4.1.1 --- Use of Silicon-based Modulators in Radio-over-fiber Optical Links --- p.113 / Chapter 4.1.2 --- Novel Diode Structures and T-Rail Travelling-Wave Electrodes to Enhance the Performance of Depletion-based Modulators --- p.114 / Chapter 4.2 --- Future Work --- p.116 / Chapter Appcndix-A --- List of Symbols --- p.118 / Chapter Appcndix-B --- List of Abbreviations --- p.120 / Chapter Appcndix-C --- Principles of Various Optical Structures of Modulators --- p.123 / Chapter Appcndix-D --- Modeling of Refractive Index Change by Free-Carrier Plasma Dispersion Effcct --- p.127 / Reference --- p.131 / Publication List --- p.136

by Man Wah-Kit. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 177-180). / LIST OF FIGURES / LIST OF TABLES / abstract --- p.1 / Chapter 1. --- introduction --- p.3 / Chapter 2. --- fabrication process / Chapter 2-1 --- INTRODUCTION --- p.7 / Chapter 2-2 --- PROCESS DEVELOPMENT --- p.8 / Chapter 2-3 --- FABRICATION PROCEDURES FOR TIN FILMS --- p.10 / Chapter 2-4 --- FABRICATION PROCEDURES FOR TIN OXIDE FILMS --- p.14 / Chapter 2-5 --- FABRICATION THEORY --- p.21 / Chapter 2-6 --- OXYGEN ION IMPLANTATION OF TIN FILMS --- p.24 / Chapter 3. --- structural characterization / Chapter 3-1 --- INTRODUCTION --- p.30 / Chapter 3-2 --- MICROSTRUCTURE / Chapter 3-2-1 --- SOME RELATED THEORIES OF GRAIN GROWTH / Chapter (1) --- Classical Theory of Grain Growth --- p.30 / Chapter (2) --- Hillock Growth --- p.31 / Chapter (3) --- Dislocation Creep Theory --- p.33 / Chapter (4) --- Biaxial Stress in Thin Films --- p.35 / Chapter (5) --- Surface Cluster Growth --- p.37 / Chapter 3-3 --- EXPERIMENTATION AND RESULTS / Chapter 3-3-1 --- MICROSTRUCTURAL ANALYSIS UNDER OPTICAL MICROSCOPE --- p.39 / Chapter 3-3-2 --- THE STRESS AND HILLOCK HEIGHT ANALYSIS OF TIN OXIDE FILMS --- p.48 / Chapter 3-3-3 --- MICROSTRUCTURAL ANALYSIS BY MEANS OF ATOMIC FORCE MICROSCOPE (AFM) --- p.52 / Chapter 3-3-4 --- MICROSTRUCTURAL ANALYSIS BY X-RAY DIFFRACTION --- p.69 / Chapter 3-3-5 --- SURFACE ANALYSIS BY MEANS OF X-RAY PHOTOELECTRON SPECTROSCOPY / Chapter (1) --- Introduction --- p.73 / Chapter (2) --- Basic Theory --- p.73 / Chapter (3) --- Experimentation And Results --- p.75 / Chapter 3-3-6 --- SURFACE STUDY OF ION IMPLANTED TIN OXIDE FILMS / Chapter (1) --- Experimental Results --- p.82 / Chapter 3-4 --- DISCUSSION / Chapter 3-4-1 --- QUALITATIVE ANALYSIS OF MICROSTRUCTURE WITH THE OPTICAL MICROSCOPE --- p.88 / Chapter 3-4-2 --- QUALITATIVE ANALYSIS OF MICROSTRUCTURE WITH SEM AND AFM / Chapter (1) --- Grain Growth of Tin Oxide Films --- p.89 / Chapter (2) --- Dependence of Grain Size on Deposition Rate --- p.91 / Chapter (3) --- Dependence of Grain Size on Film Thickness --- p.92 / Chapter (4) --- Dependence of Grain Size on Substrate Temperature --- p.92 / Chapter (5) --- Origin of Hillock Growth of Tin Oxide Films --- p.93 / Chapter 3-4-3 --- FILM COMPOSITIONAL ANALYSIS WITH X-RAY DIFFRACTION --- p.95 / Chapter 3-4-4 --- SURFACE ANALYSIS WITH X-RAY PHOTOELECTRON SPECTROSCOPY …… --- p.95 / Chapter 3-4-5 --- SURFACE ANALYSIS OF OXYGEN IMPLANTED TIN FILMS --- p.96 / Chapter 4. --- OPTICAL CHARACTERIZATION / Chapter 4-1 --- INTRODUCTION --- p.98 / Chapter 4-2 --- THEORY / Chapter (1) --- Free Electron Model --- p.99 / Chapter (2) --- Effect of Film Thickness --- p.100 / Chapter (3) --- Effect of Oxygen Contents --- p.101 / Chapter (4) --- Electron-Lattice Interaction and Bandgap Studies --- p.102 / Chapter 4-3 --- EXPERIMENTATION AND RESULTS --- p.105 / Chapter 4-4 --- DISCUSSION / Chapter 4-4-1 --- BANDGAP STUDIES FOR TIN OXIDE FILMS WITH DIFFERENT DEPOSITION CONDITIONS / Chapter (1) --- Variation of Film Thickness --- p.122 / Chapter (2) --- Film Appearance --- p.123 / Chapter (3) --- Variation of Substrate Temperature --- p.123 / Chapter (4) --- Variation of Oxidation Conditions --- p.123 / Chapter 5. --- ELECTRICAL CHARACTERIZATION / Chapter 5-1 --- INTRODUCTION --- p.126 / Chapter 5-2 --- RELATED THEORY / Chapter 5-2-1 --- CURRENT-VOLTAGE (I-V) CHARACTERISTICS --- p.127 / Chapter 5-2-2 --- CAPACITANCE-VOLTAGE (C-V) CHARACTERISTICS --- p.131 / Chapter 5-2-3 --- RELATION OF ELECTRICAL TO STRUCTURAL PROPERTIES / Chapter (A) --- Effects of Deposition Conditions --- p.133 / Chapter (B) --- Effects of Grain Boundaries --- p.133 / Chapter (C) --- Effects of Ionic Impurities --- p.134 / Chapter (D) --- Effects of The Interface Properties --- p.134 / Chapter 5-2-4 --- MEASURING TECHNIQUES / Chapter (A) --- I-V Measurment of Tin Oxide on a Silicon Substrate --- p.136 / Chapter (B) --- C-V Measurement of Tin Oxide Films on Silicon Substrates --- p.137 / Chapter (C) --- Electrical Measurement of Tin Oxide Films on a Quartz Substrate --- p.137 / Chapter 5-3 --- EXPERIMENTATION --- p.138 / Chapter 5-4 --- RESULTS --- p.141 / Chapter 5-5 --- DISCUSSION / Chapter 5-5-1 --- Analysis of the Conduction Mechanism for Sn02/Si n-p Heterojunctions --- p.161 / Chapter 5-5-2 --- Analysis of the Conduction Mechanism for Sn02/Si n-n Heterojunctions --- p.162 / Chapter 5-5-3 --- Effect on the Conduction Mechanisms of Film Thickness --- p.164 / Chapter 5-5-4 --- Effect on the Conduction Mechanisms of Oxidation Time --- p.166 / Chapter 5-5-5 --- Interfacial Properties of SnOx/Si Heterojunctions --- p.166 / Chapter 5-5-6 --- Electrical Properties of SnOx Films on Quartz / Chapter (1) --- Dependence of Film Conductivity on Measuring Temperatures --- p.168 / Chapter (2) --- Dependence of Film Conductivity on Oxidation Time --- p.168 / Chapter (3) --- Dependence of Film Conductivity on Oxidation Temperature --- p.169 / Chapter (4) --- Invariance of Film Conductivity at Some Certain Measuring Temperatures --- p.170 / Chapter (5) --- Activation Energy of Sn02 Films on Quartz --- p.170 / Chapter 6. --- CONCLUSIONS --- p.172 / Chapter 7. --- FUTURE WORKS --- p.175 / Chapter 8. --- REFERENCES --- p.177 / Chapter 9. --- APPENDICES / Chapter 9-1 --- APPENDIX A List of photos --- p.181 / Chapter 9-2 --- APPENDIX B (1) ED AX results for some selected regions on samples with hillocks --- p.182 / Chapter (2) --- Relations between mean surface roughness and oxidation conditions --- p.185 / Chapter (3) --- XPS original data and typical XPS spectra for vacuum- evaporated SnO2 thin film --- p.186 / Chapter 9-3 --- "APPENDIX C Variations of optical parameters, refractive index n and extinction coefficient k in visible region with different oxidation conditions" --- p.189 / Chapter 9-4 --- APPENDIX D Electrical results for Sn02/Si heterojunction s --- p.191 / Chapter 9-5 --- APPENDIX E Calculations of band diagram for Sn02/Si heterojunctions --- p.194 / Chapter 9-6 --- APPENDIX F Resistivity versus impurity concentration for silicon at 300K --- p.196

by Lam Siu Dan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 65-67). / Text in English; abstracts in English and Chinese. / by Lam Siu Dan. / Table of contents --- p.I / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Interest in GaAs1-xNx/GaAs alloy --- p.1 / Chapter 1.2 --- Interest in growing GaAs1-xNx/GaAs using different carrier gases --- p.4 / Chapter 1.3 --- Theoretical calculation of the band gap energy of GaAs1-xNx alloy --- p.4 / Chapter 1.4 --- Advantages of using photoluminescence (PL) --- p.7 / Chapter 1.5 --- Our work --- p.9 / Chapter Chapter 2 --- Experimental setup and procedures / Chapter 2.1 --- Growth conditions of GaAs1-xNx on (001) GaAs --- p.10 / Chapter 2.2 --- X-ray diffraction / Chapter 2.2.1 --- Setup --- p.12 / Chapter 2.2.2 --- Types of X-ray measurements --- p.12 / Chapter 2.3 --- PL measurements / Chapter 2.3.1 --- Setup --- p.14 / Chapter 2.3.2 --- Types of PL measurement --- p.16 / Chapter Chapter 3 --- Results and discussions / Chapter 3.1 --- X-ray diffraction of GaAs1-xNx/GaAs / Chapter 3.1.1 --- GaAs1-xNx/GaAs grown using H2 as carrier gas --- p.17 / Chapter 3.1.2 --- GaAs1-xNx/GaAs grown using N2 as carrier gas --- p.28 / Chapter 3.1.3 --- Peak widths of the X-ray rocking curves of GaAs1-xNx/GaAs --- p.30 / Chapter 3.2 --- Room temperature (RT) and 10K PL of GaAs1-xNx/GaAs / Chapter 3.2.1 --- The energy of the NBE peak of GaAs1-xNx/GaAs --- p.32 / Chapter 3.2.2 --- The width of the NBE peak of GaAs1-xNx/GaAs --- p.44 / Chapter 3.3 --- Excitation power density (EPD) dependent PL studies of GaAs1-xNx/GaAs / Chapter 3.3.1 --- The energy of the NBE peak of GaAs1-xNx/GaAs --- p.49 / Chapter 3.3.2 --- The width of the NBE peak of GaAs1-xNx/GaAs --- p.55 / Chapter 3.4 --- Temperature dependent PL studies of GaAs1-xNx/GaAs --- p.57 / Chapter Chapter 4 --- Conclusions --- p.62 / References --- p.63

Orientador: Américo Sheitiro Tabata / Banca: Euzi Conceição Fernandes da Silva / Banca: Ligia de Oliveira Ruggiero / Banca: Sandro Martini / Banca: José Humberto Dias da Silva / 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 da Unesp / Resumo: Neste trabalho investigamos pontos quânticos de InAs sobre um substrato de GaAs crescidos pela técnica de epitaxia por feixe molecular (MBE, Molecular Beam Epitaxy). Esses pontos quânticos emitem radiação no intervalo de 1,3 üm a 1,5 üm (0,95 eV a 0,83 eV), que corresponde à janela óptica onde ocorre a mínima atenuação do sinal em redes de transmissão por fibras ópticas. Realizamos dois tipos de estudo em dois conjuntos de amostras. No primeiro caso analisamos a influência de alguns parâmetros de crescimento nas propriedades ópticas desses pontos quânticos. No segundo caso, analisamos a influência de um tratamento térmico nas propriedades ópyicas. Resultados de fotoluminescência (PL - photoluminescence) para o primeiro estudo mostraram uma grande influência da velocidade de crescimento nos espectros de emissão que apresentaram múltiplos picos, muito provavelmente associados com o estado fundamental e seus respectivos estados excitados dos pontos quânticos. Para o segundo estudo os resultados de PL mostraram que a emissão óptica consistia de uma larga banda situada entre 1,3 a 1,5 üm. Entretanto, observou-se que, após tratamento térmico durante 3 horas a uma temperatura de 550 ºC, a intensidade da PL aumentou por um fator 3. Além disso, a larga banda observada tornou-se um conjunto de pelo menos 5 picos discretos. O efeito de tratamentos térmicos em poços quânticos é bem conhecido e foi bem explorado na literatura. Em pontos quânticos, os mesmos efeitos também existem, porém, outros de igual importância tembém se apresentam. Dentre os mais importantes podemos citar a redistribuição dos tamanhos dos pontos quânticos, que podem em alguns casos limites fazer com que o ponto quântico desapareça, e a redistribuição das tensões entre a interface ponto quântico/matriz. Neste trabalho... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study investigated InAs large quantum dot on GaAs substrate grown by the techique of molecular beam epitaxy (MBE). These quantum dots emit in the spectral range of 1.3 üm and 1.5 üm (0.95 eV to 0.83 eV), which corresponds to the window of minimal signal attenuation on transmission networks by optical fiber. We have performed two kinds of study into two different sets of samples. In the first case, we have analyzed the influence of some growth parameters on the optical properties of these quantum dots. In the second one, we have analyzed the influence of a thermal treatment on the optical properties. Results of photoluminescence (PL) on the first study showed a great influence of growth velocity in the PL spectra line shape. For the second study the results of PL on an as grown sample showed that the emission signal was a large optical band in the wave length range of 1.3 üm and 1.5 üm. However, it was observed that after the thermal treatment of 3 hours at a temperature of 550 ºC, the intensity of these PL emissions increased by a factor 3. Moreover, the observed large band has become a series of at least 5 discrete peaks. The effect of heat treatments in quantum wells is well known and has been well explored in literature. In quantum dot, the same effects are expected; however, other equally important effects are also present. The most important is the size redistribution of the quantum dots, which can in some limit cases, vanish these quantum dot. Our study identified the origin of these multiple peaks, and found emissions of PL at room temperature in the optical window between 1.3 and 1.5 üm. / Doutor

O estudo da propagação da luz nas porcelanas é importante para entender seu comportamento óptico frente a situações clínicas como fotoativação de cimentos resinosos e sua resposta estética, quando observada sobre diferentes fundos. Este trabalho estudou a influência da espessura, cor, opacidade e marca comercial das porcelanas feldspáticas na propagação da luz visível, através da teoria de KubelkaMunk (KM), nos intervalos de comprimento de onda de 410500nm e de 410700nm. Foram confeccionados discos de 12,5mm por 1 mm de espessura de porcelana feldspática de duas opacidades, corpo (B) e corpo opaco (BO), das marcas Vintage Halo (HALO), Noritake Super Porcelain EX3 (NORI) e IPS dSIGN (IPS), nas cores A1, A35 e B3 (n=7). Os discos foram polidos através de uma série de lixas abrasivas até a granulação 600 e acondicionados individualmente em ambiente seco. Os discos tiveram suas curvas espectrais de refletância obtidos em contato óptico, sobre fundo branco e preto, através do uso de um espectrofotômetro com esfera de integração acoplada, no intervalo de comprimento de onda de 410700nm. As curvas de refletância foram inseridas na teoria KM, para obtenção e análise quantitativa e qualitativa das propriedades ópticas de cada material. As análises qualitativas envolveram a observação do comportamento espectral das curvas de espalhamento, absorção, espessura infinita e reflexão para todos aos materiais em função do comprimento de onda. As análises quantitativas envolveram a obtenção das espessuras ópticas estimadas em extinções crescentes de 50% (X50), 90% (X90), 95% (X95) e infinita 99.9% (X99.9), para o intervalo de comprimento de onda de 410500nm e a obtenção da espessura óptica infinita 99.9% (X) e dos Parâmetros de Translucidez (TP), estimados nas espessuras de 0.5mm (TP0.5), 1.25mm (TP1.25) e 2.00mm (TP2.00), para o intervalo de comprimento de onda de 410700nm. Os Parâmetros de Translucidez foram utilizados para avaliar o efeito de mascaramento da porcelana sobre os fundos utilizados. Os resultados mostraram que todos os fatores (cor, opacidade e marca comercial) exerceram influência para atenuar a propagação da luz através dos espécimes. De maneira geral, a maior atenuação de luz esteve ligada à porcelanas de corpo opaco e mais saturadas (cor A35 e B3). Em relação à marca comercial a porcelana IPS, atenuou de maneira geral mais luz nas cores A35 e B3 em relação às mesmas cores das marcas HALO e NORI nas espessuras ópticas estudadas. Os valores de espessura óptica infinita (espessura onde a energia transmitida é praticamente zero), para ambos os intervalos de comprimento de onda, para todos os materiais, superaram os limites de espessura clínica indicados pela literatura. Isto implicou que, no caso do intervalo de 410 a 500nm, a energia transmitida pode girar de 20 a 5% para as porcelanas de corpo, e de 10 a 5%, para as de corpo opaco e, no caso do mascaramento, as porcelanas serão mais influenciadas por fundos que apresentarem resposta colorimétrica acentuada nas regiões alaranjadas e avermelhadas do espectro visível. As análises qualitativas mostraram que para todos os materiais e espessuras a luz será preferencialmente atenuada no início do espectro, intervalo de 410 a 500nm e menos atenuada em direção ao final do espectro visível. Os resultados também mostraram que com o aumento da espessura, a atenuação aumentou, e que a relação entre espessura e atenuação é não linear. / The study of light propagation through porcelains is important to understand its optical behavior in front of clinical situations such as the photoactivation of luting cements and their esthetic responses, when observed against different backgrounds. This research studies the influence of thickness, shade, opacity, and commercial brands of feldspatic porcelains on the propagation of visible light through the Kubelka Munk Theory for the wavelength intervals of 410500nm and 410700nm. Discs with 12,5mm in diameter and thickness of 1mm were prepared with feldspatic porcelain in two opacities, body (B) and opaque body (BO), three commercial brands; Vintage Halo (HALO), Noritake Super Porcelain EX3 (NORI), and IPS dSIGN (IPS), and three shades, A1, A35, and B3 (n=7). The discs were polished with a series of waterproof sandpapers down to a #600 grade sandpaper, and individually stored in a dry environment. The spectral reflectance curves were acquired from the disks on optical contact, against white and black backgrounds, with a spectrometer with a diffuse reflectance attachment (an attached integration sphere), in the wavelength interval of 410700nm. The reflectance spectra were inserted in the KM theory to quantitatively and qualitatively obtain and analyze the optical properties of each material. The qualitative analyses were obtained from the observation of the spectral behavior of scattering, absorption, infinite optical thickness, and reflection spectra for all materials as a function of the wavelength. The quantitative analyses involved obtaining the predicted optical thicknesses in extinctions with increments of 50% (X50), 90% (X90), 95% (X95) and infinite 99.9% (X99.9), for the wavelength interval of 410500nm and the obtaining of the infinite optical thickness 99.9% (X) and the translucency parameter (TP) estimated as 0.5mm (TP0.5), 1.25mm (TP1.25) e 2.00mm (TP2.00) thicknesses, for the wavelength interval of 410700nm. The Translucency parameters were used to evaluate the porcelain masking effect against the tested backgrounds. The results showed that all factors (Shade, Opacity, and Commercial Brand) exerted influence to attenuate the light propagation through the specimens. In general, a higher light attenuation was linked to porcelains exhibiting more saturated shades (A35, and B3) and body opaque types. The commercial brand IPS porcelain shades A35 and B3, generally attenuated more light than the same shades of HALO and NORI for the studied optical thicknesses. The infinite optical thicknesses values (thicknesses where the transmitted light is close to zero) is above the clinical thickness reported in the literature for all materials and both wavelength intervals. This fact implied that regarding the 410500nm interval, the body porcelain could transmit from 20 to 5% of the energy, while the opaque body transmits from 10 to 5%. The masking effect of the porcelains will be increasingly translucid against the background with increased colorimetric response on the Red Orange regions of the visible spectra. The qualitative analysis showed that for all materials and thicknesses, the light will preferably be attenuated in the beginning of the spectra, on the 410500nm interval e and will be less attenuated towards the ending of the visible spectra. The results also showed that the attenuation increased with the increase of the thickness, and the relationship between thickness and attenuation is nonlinear.