Highly efficient LEDs and photovoltaic cells based on spin coated films of layered Ruddlesden-Popper hybrid perovskites (RPP) have been recently reported. The electronic structure and phase composition of these films remains an open question, with diverse explanations offered accounting for the excellent device performance. Here we report x-ray and optical characterization of hot cast RPP thin films, emphasizing the distribution of structural and electronic properties through the film depth. Our results indicate an at least 70% phase pure n=3 film results from casting a stoichiometric solution of precursors, with minor contributions from n=2 and n=4 phases. We observe a strong correspondence between the predicted single-crystal RPP reciprocal lattice and measured RPP film wide angle scattering pattern, indicating a highly ordered [101] oriented film. This correspondence is broken at the air-film interface where new scattering peaks indicate the existence of a long wavelength structural distortion localized near the films surface. Using transient absorption spectroscopy, we show that the previously detected luminescent mid-gap states are localized on the films surface. Investigating films of varying thickness, we determine the photo-excited carrier dynamics are dominated by diffusion to this interface state, and extract an excitonic diffusivity of 0.18cm2s-1. We suggest that the observed surface distortion is responsible for the creation of luminescent mid-gap states.

Chow Chi Fai. / Thesis submitted in: August 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract / Abstract (Chinese) / A cknowledgements / Table of Contents / List of Figures / List of Tables / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- The need for light emission from silicon --- p.1-1 / Chapter 1.2 --- Silicon-based light emitting material 1 - --- p.2 / Chapter 1.3 --- Literature overview --- p.1-4 / Chapter 1.4 --- Project goal --- p.1-10 / Reference --- p.1-11 / Chapter Chapter 2 --- Experimental details / Chapter 2.1 --- Introduction --- p.2-1 / Chapter 2.2 --- Sample preparation techniques --- p.2-1 / Chapter 2.2.1 --- MEVVA ion implantation --- p.2-1 / Chapter 2.2.2 --- PL samples preparation conditions --- p.2-3 / Chapter 2.2.3 --- EL samples preparation conditions --- p.2-4 / Chapter 2.3 --- Characterization techniques --- p.2-7 / Chapter 2.3.1 --- Photoluminescence spectroscopy (PL) --- p.2-7 / Chapter 2.3.2 --- Electroluminescence spectroscopy (EL) --- p.2-9 / Chapter 2.3.3 --- Rutherford backscattering spectroscopy (RBS) --- p.2-10 / Chapter 2.3.4 --- X-ray diffraction (XRD) --- p.2-12 / Chapter 2.3.5 --- Transmission electron microscopy (TEM) --- p.2-13 / Reference --- p.2-15 / Chapter Chapter 3 --- Resutls and Discussions / Chapter 3.1 --- RBS results --- p.3-1 / Chapter 3.2 --- XRD results --- p.3-8 / Chapter 3.3 --- TEM results --- p.3-12 / Chapter 3.3.1 --- Effects of the implantation energy on the microstructure of samples --- p.3-13 / Chapter 3.3.2 --- Effects of the implantation dose on the microstructure of samples --- p.3-16 / Chapter 3.4 --- Photoluminescence results --- p.3-19 / Chapter 3.4.1 --- Effect of implantation energy on the PL --- p.3-19 / Chapter 3.4.2 --- Effect of FA temperature on the PL --- p.3-24 / Chapter 3.4.3 --- Effect of FA duration on the PL --- p.3-26 / Chapter 3.4.4 --- Effect ofRTA duration on the PL --- p.3-28 / Chapter 3.4.5 --- Effect ofRTA temperature on the PL --- p.3-30 / Chapter 3.4.6 --- Effect of implantation dose on the PL --- p.3-32 / Chapter 3.4.7 --- Si band edge enhancement --- p.3-34 / Chapter 3.4.8 --- Photoluminescence spectra as a function of excitation power density --- p.3-37 / Chapter 3.4.9 --- Photoluminescence spectra as a function of measurement temperature --- p.3-45 / Chapter 3.5 --- Electroluminescence results --- p.3-52 / Chapter 3.5.1 --- EL quantum efficiency --- p.3-60 / Reference --- p.3-61 / Chapter Chapter 4 --- Conclusion and future works / Chapter 4.1 --- Conclusion --- p.4-1 / Chapter 4.2 --- Future works --- p.4-2 / Appendix I / Appendix II

石墨烯，由單層碳原子緊密排列成蜂巢狀的晶體結構，擁有卓越的電學性能和光學性能。這些優異的性能包括：極高的電子遷移率，超寬的吸收光譜，栅電壓調控光躍遷性質，飽和吸收性質。石墨烯的獨特光學性質已經被用來製造多種高性能的光電器件，包括光電探測器， 飽和吸收器， 光調製器和四波混頻的介質。同時，石墨烯的製造工藝可以與現代半導體標準製造工藝相兼容， 加上它穩定的化學性質， 石墨烯非常有潛力在未來半導體工業發展中發揮重要作用。 / 單層石墨烯可以透過97.7% 垂直入射的光，吸收2.3% 左右，並且吸收的光頻非常寬。雖然對於單層碳原子結構，這個吸收率很大，但是在一些器件中，我們需要更高的光吸收率。爲了突破單層石墨烯光吸收的極限，一種可行的辦法是延長石墨烯與光相互作用的長度。將單層石墨烯轉移到長的硅波導上，可以延長石墨烯與光作用的長度。除了線性光吸收特性，石墨烯的飽和吸收特性也有廣泛的應用。很多脉衝激光發生器是利用被動鎖模的原理，即激光器中的飽和吸收器將連續的光波轉變成頻率固定的脉衝。石墨烯已經被證明是恢復速度快、調製範圍大的飽和吸收器。 但是，石墨烯和硅波導結合作為飽和吸收器的特性和它們的應用還從來沒有被研究過。 / 在論文中，我們研究了石墨烯轉移到硅波導后的線形光學性質和飽和吸收特性。首先我們討論了石墨烯轉移的方法，然後我們通過實驗調查了石墨烯在貴波導上的線形光學性質和飽和吸收特性。爲了研究石墨烯/硅波導在被動鎖模光纖激光器中的作用，我們利用石墨烯/硅波導作為飽和吸收器製造了一個光纖激光器。之後，通過在激光腔體中加入可调滤波器， 我們用成功的演示了波長可調製被動鎖模光纖激光器。 / 多脉衝激光光源在光纖通信，測量學和光學器件性能鑒定中有重要作用。所以研究緊湊、穩定並且價格實惠的多脉衝鎖模激光器非常有意義。爲了實現多脉衝鎖模光纖激光器，我們將硅基濾波器和石墨烯/硅波導集成在一起. 在論文中，我們設計并優化了能被應用於多脉衝鎖模激光器的寬帶寬濾波器凹凸光栅。 / Graphene, a single 2D sheet of carbon atoms arranged in a honeycomb lattice, has superior electrical and optical properties including extremely high charge-carrier mobility, broadband optical absorption, gate-variable optical transitions and saturable absorptions. Its unique optical properties have led to a range of promising optoelectronic devices, such as photo detectors, saturable absorbers, optical modulators and nonlinear media for four-wave mixing. Graphene’s complementary metal-oxide-semiconductor (CMOS) integration processes at wafer scale and its electrochemical stability make it a promising candidate for post CMOS electronics. / Monolayer grapheme transmits 97.7% of the normal incident light and absorbs 2.3%, independent of wavelength. In order to overcome the challenge of limited absorption of a monolayer and better exploit graphene optical properties, a long interaction length is needed. By integrating graphene directly on top of silicon waveguides, longer light/graphene interactions can be achieved. In addition to the linear optical properties of the graphene, its saturable absorption also finds useful applications. Many ultra-short pulse lasers are based on passive mode-locking, where a saturable absorber turns continuous wave output of the laser into a train of optical pulses. And graphene has been shown to make an excellent saturable absorber. However, the saturable absorption behavior of graphene-silicon wavguides and their applications have never been studied. / In this thesis, the linear and saturable absorption of monolayer graphene films transferred onto silicon waveguide are investigated. The transfer process of monolayer graphene to silicon waveguides is studied and linear and saturable absorption measurements are carried out. To investigate applications of graphene-silicon waveguides, a passive mode-lock fiber lasers in which graphene-silicon waveguides act as saturable absorbers to mode-lock pulses is constructed. By adding a tunable filter in cavity, a tunable mode-locked fiber laser based on graphene-silicon waveguide is demonstrated. / Multi-wavelength pulse sources are important for applications including optical fiber communication, instrumentation, and photonic component characterization. The availability of compact, reliable and cost effective multi-wavelength mode-locked lasers is of great importance. We also hope to build multiwavelength mode-locked fiber lasers by integrating CWDM silicon filters with graphene-silicon waveguides. The design process and optimization of a silicon filter called echelle grating is demonstrated. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Shi, Zerui. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Abstracts also in Chinese. / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Photonic Integrated Circuit (PIC) --- p.1 / Chapter 1.2 --- Silicon on Insulator (SOI) Photonics --- p.3 / Chapter 1.2.1 --- SOI Waveguides --- p.5 / Chapter 1.2.2 --- SOI Waveguide Based Wavelength Division Multiplexing --- p.6 / Chapter 1.3 --- Graphene Photonics --- p.9 / Chapter 1.3.1 --- Band Structure of Monolayer Graphene --- p.9 / Chapter 1.3.2 --- Optical Absorption of Graphene --- p.13 / Chapter 1.3.3 --- Graphene Based Passive Mode-Locked Fiber Lasers --- p.18 / Chapter 1.4 --- Motivation --- p.22 / Chapter 1.5 --- Thesis Outline --- p.23 / Chapter 1.6 --- Reference --- p.24 / Chapter Chapter 2: --- Optical Properties of Graphene-Silicon Waveguides --- p.27 / Chapter 2.1 --- Fabrication and Transfer Process of Graphene-Silicon Waveguides --- p.28 / Chapter 2.1.1 --- Fabrication of SOI Waveguides --- p.28 / Chapter 2.1.2 --- Transfer Process of Monolayer Graphene onto SOI Waveguides --- p.29 / Chapter 2.2 --- Linear Optical Absorption of Graphene-Silicon Waveguides --- p.35 / Chapter 2.2.1 --- Introduction to Photoexcitation in Monolayer Graphene --- p.35 / Chapter 2.2.2 --- Experimental Results of Linear Absorption --- p.37 / Chapter 2.3 --- In-Plane Saturable Absorption of Graphene-Silicon Waveguides --- p.38 / Chapter 2.3.1 --- Experimental Result of In-Plane Saturable Absorption of Graphene-Silicon Waveguides --- p.39 / Chapter 2.3.2 --- Mechanism of Saturable Absorption of Graphene-Silicon Waveguides --- p.42 / Chapter 2.4 --- Summary --- p.44 / Chapter 2.5 --- Reference --- p.45 / Chapter Chapter 3: --- Hybrid Graphene-Silicon Waveguides Based Mode-Locked Fiber Lasers --- p.47 / Chapter 3.1 --- Background of Graphene Based Mode-Locked Fiber Lasers --- p.47 / Chapter 3.1.1 --- Passive Mode-Locked Lasers Fundamentals --- p.47 / Chapter 3.1.2 --- Review of Recent Works of Graphene Based Mode-Locked Fiber Lasers . --- p.52 / Chapter 3.2 --- Hybrid Graphene-Silicon Waveguides Based Mode-Locked Fiber Lasers --- p.55 / Chapter 3.2.1 --- Experimental Set Up and Results --- p.55 / Chapter 3.2.2 --- Discussion --- p.59 / Chapter 3.3 --- Tunable Graphene-Silicon Waveguides Based Mode-Locked Fiber Lasers --- p.62 / Chapter 3.4 --- Summary --- p.66 / Chapter 3.5 --- Reference --- p.66 / Chapter Chapter 4: --- Conclusion and Future Work --- p.68 / Chapter 4.1 --- Conclusion --- p.68 / Chapter 4.2 --- Future Work --- p.69 / Chapter 4.2.1 --- Design and Simulation Results of Echelle Grating --- p.69 / Chapter 4.2.2 --- Optimization and Experiment Results of Echelle Gratings --- p.77 / Chapter 4.2.3 --- Integration of Echelle Grating with SOI Waveguides --- p.82 / Chapter 4.3 --- Summary --- p.84 / Chapter 4.4 --- Reference --- p.85 / Chapter APPENDIX A: --- PUBLICATION LIST --- p.86 / Chapter APPENDIX B: --- LIST OF FIGURES --- p.87 / Chapter APPENDIX C: --- LIST OF TABLES --- p.91 / Chapter APPENDIX D: --- atlab Code of Simulation of Echelle Grating --- p.92

by Kwan Chi Man Simon. / Abstract also in Chinese. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references. / Abstract --- p.i / Abstract (Chinese) --- p.iii / Acknowledgment --- p.iv / Contents --- p.v / Abbreviations --- p.viii / List of Figures --- p.xiv / List of Tables --- p.xvii / Chapter 1. --- Introduction --- p.1 / Chapter 2. --- Theoretical background --- p.4 / Chapter 2.1 --- Static laser light scattering --- p.5 / Chapter 2.2 --- Dynamic laser light scattering --- p.5 / Chapter 2.3 --- Gel Permeation Chromatography --- p.6 / Chapter 2.4 --- Chain Flexibility --- p.9 / Chapter 2.4.1 --- Flexible chains --- p.9 / Chapter 2.4.2 --- Stiff chains --- p.12 / Chapter 2.5 --- Calibration between translational diffusion coefficient D and molar mass M --- p.14 / Chapter 2.5.1 --- Conversion between line-Width and molar Mass distributions --- p.14 / Chapter 2.5.2 --- Using a set of Narrowly Distributed Standards --- p.15 / Chapter 2.5.3 --- Using Two or More Broadly Distributed Samples --- p.16 / Chapter 2.6 --- "Calibration by off-line GPC, Static and Dynamic LLS" --- p.16 / Chapter 2.7 --- References --- p.19 / Chapter 3. --- Experimental --- p.21 / Chapter 3.1 --- Laser Light Scattering Instrumentation --- p.21 / Chapter 3.2 --- Refractive index increment measurement --- p.23 / Chapter 3.3 --- Gel permeation chromatography --- p.24 / Chapter 3.4 --- References --- p.25 / Chapter 4. --- Laser Light Scattering Studies of Soluble High Performance Fluorine- containing Polyimides --- p.26 / Chapter 4.1 --- Introduction --- p.26 / Chapter 4.2 --- Sample Preparation --- p.28 / Chapter 4.3 --- Results and Discussion --- p.28 / Chapter 4.4 --- Conclusion --- p.40 / Chapter 4.5 --- References --- p.42 / Chapter 5. --- Characterization of novel optically active conjugated polyarylenes and poly(aryleneethynylene)s by a combination of Laser Light Scattering and Gel Permeation Chromatography --- p.45 / Chapter 5.1 --- Introduction --- p.45 / Chapter 5.2 --- Sample Preparation --- p.48 / Chapter 5.3 --- Results and Discussion --- p.48 / Chapter 5.4 --- Conclusion --- p.56 / Chapter 5.5 --- References --- p.61 / Appendix --- p.62 / Chapter A.1 --- Static laser light scattering --- p.62 / Chapter A.1.1 --- Scattering from a small particle --- p.62 / Chapter A. 1.2 --- Scattering from a large particle --- p.62 / Chapter A. 1.3 --- Scattering by macroscopic systems and Theory of Fluctuations --- p.65 / Chapter A.1.3.1 --- Scattering by gases and liquids --- p.67 / Chapter A. 1.4 --- Scattering by solutions of small molecules --- p.68 / Chapter A. 1.4.1 --- Scattering from polymer solution --- p.70 / Chapter A.2 --- Dynamic laser light scattering --- p.71 / Chapter A.2.1 --- Line-width measurement --- p.75 / Chapter A.2.2 --- Data analysis --- p.77

by T.W. Chui. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 79-81). / Text in English; abstract also in Chinese. / by T.W. Chui. / Titleage --- p.i / Acknowledgments --- p.ii / Abstract --- p.iii / Table of contents --- p.v / Chapter Chapter 1 --- Introduction --- p.1 / Figure Captions --- p.16 / Chapter Chapter 2 --- Meauserment of first hyperpolarizability / Chapter 2.1 --- Electric Field Induced Second Hamonics (EFISH) --- p.21 / Chapter 2.2 --- Hyper-Rayleigh Scattering (HRS) --- p.23 / Chapter 2.3 --- Internal reference method and External reference method --- p.26 / Figure Captions --- p.28 / Chapter Chapter 3 --- Experimental Setup / Chapter 3.1 --- Design of experimental setup --- p.30 / Chapter 3.2 --- Alignment --- p.32 / Chapter 3.3 --- ower --- p.33 / Chapter 3.4 --- Samples --- p.33 / Figure Captions --- p.35 / Chapter Chapter 4 --- Measurement of first hyperpolarizability of selected molecules / Chapter 4.0 --- Introduction --- p.40 / Chapter 4.1 --- Result of spectral study of the scattered signal from CV --- p.43 / Chapter 4.2 --- Result of the first hyperpolarizability of CV --- p.46 / Chapter 4.3 --- HRS measurement with DANS --- p.47 / Figure Captions --- p.51 / Graphs --- p.52 / Tables --- p.57 / Chapter Chapter 5 --- Studies of the depolarization ratio of HRS and fluorescence light from CV / Chapter 5.0 --- Introduction --- p.59 / Chapter 5.1 --- Experimental setup for the measurement of depolarization ratio --- p.60 / Chapter 5.2 --- Measurement of depolarization ratio forNA at 532nm --- p.61 / Chapter 5.3 --- Measurement of depolarization ratio for CV at 532nm --- p.62 / Chapter 5.4 --- Measurement of depolarization ratio for fluorescence light from CV --- p.63 / Figure Captions --- p.68 / Graphs --- p.71 / Tables --- p.75 / Chapter Chapter 6 --- Conclusions --- p.77 / References --- p.79

Xu Yan = 納米銅(銅的氧化物)與三氧化二鋁復合物薄膜的製備和特性研究 / 許燕. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 50-51). / Text in English; abstracts in English and Chinese. / Xu Yan = Na mi tong (tong de yang hua wu) yu san yang hua er lv fu he wu bo mo de zhi bei he te xing yan jiu / Xu Yan. / Abstract --- p.i / 摘要 --- p.ii / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Figures --- p.viii / List of Tables --- p.xi / Chapter CHAPTER 1 --- Introduction / Chapter 1.1 --- Nanostructured Materials --- p.1 / Chapter 1.2 --- Objective of this Work --- p.1 / Chapter CHAPTER 2 --- Background / Chapter 2.1 --- Correlation of AES-CuLMM spectrum and Cu nanocluster size --- p.3 / Chapter 2.1.1 --- Typical AES-CuLMM spectra --- p.3 / Chapter 2.1.2 --- A simplified model --- p.4 / Chapter 2.1.3 --- correlation of AES-CuLMM spectra and the simplified model --- p.4 / Chapter 2.2 --- Previous works --- p.5 / Chapter CHAPTER 3 --- Instrumentation / Chapter 3.1 --- Sputtering --- p.6 / Chapter 3.1.1 --- Principles of sputtering --- p.6 / Chapter 3.1.1.1 --- Concepts of sputtering --- p.6 / Chapter 3.1.1.2 --- Initiating the plasma --- p.8 / Chapter 3.1.1.3 --- Depositing a film onto the substrate --- p.8 / Chapter 3.1.2 --- Radio-frequency (RF) magnetron sputtering --- p.9 / Chapter 3.1.2.1 --- RF sputtering --- p.9 / Chapter 3.1.2.2 --- Magnetron Sputtering --- p.10 / Chapter 3.2 --- Deposition system --- p.10 / Chapter 3.2.1 --- Instrumentation --- p.11 / Chapter 3.2.1.1 --- Vacuum system --- p.11 / Chapter 3.2.1.2 --- Sputter target and power supplies --- p.12 / Chapter 3.2.1.3 --- Substrate mounting --- p.13 / Chapter 3.2.2 --- Experimental --- p.13 / Chapter 3.3 --- X-ray Photoelectron Spectroscopy (XPS) --- p.14 / Chapter 3.3.1 --- Basic Principles --- p.14 / Chapter 3.3.2 --- Instrumentation --- p.17 / Chapter 3.3.3 --- Qualitative and quantitative analysis --- p.17 / Chapter 3.3.3.1 --- Spectra interpretations --- p.17 / Chapter 3.3.3.2 --- X-ray emission line width --- p.18 / Chapter 3.3.3.3 --- Qualification --- p.18 / Chapter 3.3.3.3.1 --- Chemical composition --- p.18 / Chapter 3.3.3.3.2 --- Sputter depth profiling --- p.18 / Chapter 3.3.3.3.3 --- Auger parameter --- p.19 / Chapter 3.4 --- Transmission Electron Microscopy (TEM) --- p.19 / Chapter 3.4.1 --- An overview of TEM --- p.19 / Chapter 3.4.2 --- Imaging mode and diffraction mode --- p.21 / Chapter 3.4.3 --- Electron-Specimen interactions --- p.21 / Chapter 3.4.3.1 --- Elastic scattering --- p.22 / Chapter 3.4.3.2 --- Inelastic scattering --- p.22 / Chapter 3.4.4 --- Imaging mechanisms for TEM --- p.23 / Chapter 3.4.4.1 --- Mass-thickness contrast --- p.23 / Chapter 3.4.4.2 --- Diffraction contrast --- p.23 / Chapter 3.4.5 --- TEM sample preparation --- p.25 / Chapter CHAPTER 4 --- Chemical and Structure Characterization of Cu(CuOx)/Al2O3 Composite Thin Films / Chapter 4.1 --- Overview --- p.26 / Chapter 4.2 --- Results and discussions --- p.26 / Chapter 4.2.1 --- Set I: Achieving the stoichiometry of A1203 matrix --- p.26 / Chapter 4.2.2 --- Set II: keeping A1203 stoichiometry and studying on the correlation of CuLMM spectra and average Cu cluster size --- p.32 / Chapter 4.2.2.1 --- Chemical information obtained by XPS --- p.32 / Chapter 4.2.2.2 --- Nanostructure studied by TEM --- p.38 / Chapter 4.2.2.3 --- Mechanical properties inspected by nano-indentation --- p.43 / Chapter 4.2.2.4 --- Optical properties --- p.43 / Chapter 4.2.3 --- Set III: Duration of deposition --- p.44 / Chapter 4.2.4 --- Set VI: Pressure effect on the average size of Cu nanoclusters --- p.45 / Chapter CHAPTER 5 --- Conclusions --- p.48 / References --- p.50

O objetivo principal deste projeto foi o estudo das propriedades ópticas de estruturas semicondutoras do tipo super-redes, formadas a partir da heteroestrutura de GaAs/AlAs, crescida através da técnica de Epitaxia por Feixe Molecular. No trabalho apresentamos estudos feitos em super-redes do tipo (GaAs)n/(AlAs)n, crescidas em substratos semi-isolantes e orientados nas direções (100) e (nl1) com n=1,2,3,5,7 e nas polaridades A e B. Para cada periodicidade (n x n), as estruturas foram crescidas simultaneamente num mesmo porta amostra e sob as mesmas condições. As amostras foram estudadas através das técnicas de fotoluminescência a baixa temperatura e em função da temperatura. São apresentados também resultados preliminares de um estudo feito com a técnica de fotoluminescência de excitação. A técnica de difração de elétrons de alta energia foi utilizada durante o crescimento epitaxial para aferição da periodicidade da estrutura. A eficiência quântica, a posição do pico de luminescência estão fortemente correlacionados com a direção de crescimento. As medidas de fotoluminescência em função da temperatura mostram também um decréscimo anômalo da largura de linha. A partir dos resultados ópticos foi proposta a formação de microestruturas de mais baixa diemnsionalidade nos poços, formadas por flutuações nas interfaces (microrugosidades), e originárias do modo de crescimento adotado (sem interrupção nas interfaces). O comportamento óptico observado é semelhante ao de estruturas de mais baixa dimensionalidade (pontos quânticos). Este efeito é acentuado nas direções (311) e (21l), devido a própria morfologia da superfície / The main objective of this work was the study of the optical properties of semiconductors superlattices, formed by the (GaAs)n,/(AlAs)n, heterostructure, and grown by technique of Molecular Beam Epitaxy. In the work, we presented studies in (GaAs)n/(AlAs)n, superlattices, grown on semi-insulating substrates oriented in planes (100) and (n11) with n=l, 2, 3, 5, 7 and in the polarities A and B. For each periodicity (n x n), the structures were simultaneously grown in a same sample holder, and under the same conditions. The samples were studied by the photoluminescence techniques at low temperature and in function of the temperature. Preliminares results of a study done with the technique of excitation photoluminescence are also presented. The technique of high energy eletron difraction was used during the epitaxial growth for the monitoring of the periodicity of the structure. The quantum efficiency and the positions of the luminescence peak are strongly correlated with the growth direction. The photoluminescence measures in function of the temperature also show an anomalous decrease in linewidth. The analyses of the optical results shown the possibility of low dimension microstructures formation in the wells, due to the interfaces fluctuations, and related with the growth mode (without interruption at the interface). The observed optical behavior is similar to the observed in the structures of lower dimensionality (quantum dots). This effect is accentuated in the plans (311) and (211), due to the morphology of the surface

Fabrication of integrated photonic devices and circuits in a CMOS-compatible process or foundry is the essence of the silicon photonic platform. Optical devices in this platform are enabled by the high index contrast between silicon and silicon on insulator. These devices offer potential benefits when integrated with existing and emerging high performance microelectronics. Integration of silicon photonics with small footprints and power-efficient and high-bandwidth operation has long been cited as a solution to existing issues in high performance interconnects for telecommunications and data communication. Stemming from this historic application in communications, new applications in sensing arrays, biochemistry, and even entertainment continue to grow. However, for many technologies to successfully adopt silicon photonics and reap the perceived benefits, the silicon photonic platform must extend toward development of a full ecosystem. Such extension includes implementation of low cost and robust electronic-photonic packaging techniques for all applications. In an ecosystem implemented with services ranging from device fabrication all the way to packaged products, ease-of-use and ease-of-deployment in systems that require many hardware and software components becomes possible. With the onset of the Internet of Things (IoT), nearly all technologies—sensors, compute, communication devices, etc.—persist in systems with some level of localized or distributed software interaction. These interactions often require a level of networked communications. For silicon photonics to penetrate technologies comprising IoT, it is advantageous to implement such devices in a hardware-software integrated way. Meaning, all functionalities and interactions related to the silicon photonic devices are well defined in terms of the physicality of the hardware. This hardware is then abstracted into various levels of software as needed in the system. The power of hardware-software integration allows many of the piece-wise demonstrated functionalities of silicon photonics to easily translate to commercial implementation. This work begins by briefly highlighting the challenges and solutions for transforming existing silicon photonic platforms to a full-fledged silicon photonic ecosystem. The highlighted solutions in development consist of tools for fabrication, testing, subsystem packaging, and system validation. Building off the knowledge of a silicon photonic ecosystem in development, this work continues by demonstrating various levels of hardware-software integration. These are primarily focused on silicon photonic interconnects. The first hardware-software integration-focused portion of this work explores silicon microring-based devices as a key building block for greater silicon photonic subsystems. The microring’s sensitivity to thermal fluctuations is identified not as a flaw, but as a tool for functionalization. A logical control system is implemented to mitigate thermal effects that would normally render a microring resonator inoperable. The mechanism to control the microring is extended and abstracted with software programmability to offer wavelength routing as a network primitive. This functionality, available through hardware-software integration, offers the possibility for ubiquitous deployment of such microring devices in future photonic interconnection networks. The second hardware-software integration-focused portion of this work explores dynamic silicon photonic switching devices and circuits. Specifically, interactions with and implications of high-speed data propagation and link layer control are demonstrated. The characteristics of photonic link setup include transients due to physical layer optical effects, latencies involved with initializing burst mode links, and optical link quality. The impacts on the functionalities and performance offered by photonic devices are explored. An optical network interface platform is devised using FPGAs to encapsulate hardware and software for controlling these characteristics using custom hardware description language, firmware, and software. A basic version of a silicon photonic network controller using FPGAs is used as a tool to demonstrate a highly scalable switch architecture using microring resonators. This architecture would not be possible without some semblance of this controller, combined with advanced electronic-photonic packaging. A more advanced deployment of the network interface platform is used to demonstrate a method for accelerating photonic links using out-of-band arbitration. A first demonstration of this platform is performed on a silicon photonic microring router network. A second demonstration is used to further explore the feasibility of full hardware-software integrated photonic device actuation, link layer control, and out-of-band arbitration. The demonstration is performed on a complete silicon photonic network with both spatial switching and wavelength routing functionalities. The aforementioned hardware-software integration mechanisms are rigorously tested for data communications applications. Capabilities are shown for very reliable, low latency, and dynamic high-speed data delivery using silicon photonic devices. Applying these mechanisms to complete electronic-photonic packaged subsystems provides a strong path to commercial manifestations of functional silicon photonic devices.

Lei, Dangyuan = 表面等離子交叉耦合協助氧化鋅發射的理論和實驗研究 / 雷黨願. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 81-85). / Abstracts in English and Chinese. / Lei, Dangyuan = Biao mian deng li zi jiao cha ou he xie zhu yang hua xin fa she de li lun he shi yan yan jiu / Lei Dangyuan. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivations --- p.1 / Chapter 1.2 --- Thesis outline --- p.3 / Chapter 2 --- Background and Proposition --- p.7 / Chapter 2.1 --- Surface plasmon mediated emission from semiconductor --- p.7 / Chapter 2.1.1 --- General mechanism --- p.7 / Chapter 2.1.2 --- Formulation of SP coupling --- p.10 / Chapter 2.1.2.1 --- Derivation of dispersion relation --- p.10 / Chapter 2.1.2.2 --- Plasmonic density of states (DOS) --- p.13 / Chapter 2.1.2.3 --- Field distribution in dielectric/metal/dielectric System --- p.13 / Chapter 2.1.2.4 --- Determination of Purcell factor (Fp) --- p.16 / Chapter 2.1.3 --- Emission enhancement from metal-capped ZnO --- p.17 / Chapter 2.2 --- Proposal for making high efficiency top-emitting LED --- p.22 / Chapter 3 --- Experimental Setup and Measurement System --- p.24 / Chapter 3.1 --- Sample preparation --- p.24 / Chapter 3.1.1 --- Radio frequency magnetron sputtering --- p.24 / Chapter 3.1.2 --- Spin-coating --- p.27 / Chapter 3.1.3 --- Rapid thermal annealing --- p.29 / Chapter 3.2 --- Optical characterizations --- p.29 / Chapter 3.2.1 --- Transmittance measurement --- p.29 / Chapter 3.2.2 --- Photoluminescence (PL) measurement --- p.31 / Chapter 3.2.3 --- EDX for composition measurement --- p.32 / Chapter 4 --- Theoretical Simulations and Experimental Results --- p.36 / Chapter 4.1 --- Tunable surface plasmon resonance by using metal alloys --- p.36 / Chapter 4.1.1 --- Dielectric constants calculation --- p.37 / Chapter 4.1.2 --- Dispersion relation of alloy/Si02 --- p.41 / Chapter 4.1.3 --- Plasmonic density of states and Purcell factor of alloy/semiconductor --- p.43 / Chapter 4.1.3.1 --- Air/AlxAg1-x/ZnO system --- p.43 / Chapter 4.1.3.2 --- Air/AlxAul-x/ZnTe --- p.46 / Chapter 4.1.3.3 --- Air/ AgxAul-x/CdSe system --- p.48 / Chapter 4.1.4 --- Experimental results of AlxAgl-x/ZnO --- p.52 / Chapter 4.1.5 --- Discussion and mini-conclusion --- p.56 / Chapter 4.2 --- Enhanced forward emission from metal-insulator-metal/ZnO by coupled surface plasmon --- p.57 / Chapter 4.2.1 --- Plasmon modes in metal-insulator-metal (MIM) --- p.57 / Chapter 4.2.2 --- Transmittance simulation of MIM and MIMIM --- p.63 / Chapter 4.2.3 --- Transmittance measurement of MIM --- p.68 / Chapter 4.2.4 --- Transmittance and photoluminescence of MIM/ZnO. --- p.73 / Chapter 4.2.5 --- Discussion and mini-conclusion --- p.78 / Chapter 5 --- Conclusions --- p.79 / Chapter 6 --- References --- p.81

Polymer stabilized cholesteric liquid crystals (PSCLCs) provide many advantages over other electro-optical materials. The unique helical structure of the cholesteric liquid crystal (CLC) creates a natural gradient for light interacting across each CLC domain layer. Not only does the CLC helical structure greatly increase the bandwidth tuning and broadening range, it also allows CLCs to act as a polarizer, notch filter, reflector, and optical rotator all in one material. However, while many novel PSCLC materials have been created, little is understood about how complex initial system interactions affect final electro-optical (e-o) properties.1,2 In this work, the principal variables affecting PSCLC blue shift electro-optical behavior have been determined through structural analysis and measurement of electro-optical properties. Typical PSCLC materials must meet both formulation and photopolymerization processing requirements to display blue shift e-o properties. Threshold photoinitiator concentrations (0.5-1.5 wt%) and morpholine containing group concentrations (0.25-1.0 wt%) were both shown to be primary factors, along with sufficient UV exposure time (10-30 min) and light intensity (500 mW/cm2, 365 nm), for PSCLC blue shift bandwidth tuning/broadening to occur. Morpholine was initially identified as a component of photoinitators Irgacure 369 and 907 and was proven to increase PSCLC ion density altering LC-polymer network interactions with several proposed theories included later in this work. The use of an appropriate morpholine containing LC monomer to directly incorporate morpholine into the LC-polymer network was shown to greatly improve PSCLC sample stability. Through the results of this research we successfully induced blue shift e-o behavior in a previous red shift only PSCLC using only 30% of the UV exposure that a model PSCLC blue shift sample required while extending the blue shift broadening range over threefold (from 75 nm to 250 nm). The fundamental understanding and design of PSCLC systems described herein serves as a starting point for engineering PSCLC materials with specific and desirable electro-optical properties.