Hong Liang = 用化学气相淀积方法生长氮化物纳米材料 / 洪亮. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Hong Liang = Yong hua xue qi xiang dian ji fang fa sheng chang dan hua wu na mi cai liao / Hong Liang. / Acknowledgements --- p.ii / Abstract --- p.iii / Contents --- p.v / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Motivation --- p.2 / Chapter 1.2.1 --- A1N and AlGaN nanowires --- p.2 / Chapter 1.2.2 --- CVD --- p.3 / Chapter 1.3 --- Our work --- p.3 / Chapter Chapter 2 --- Experiment --- p.7 / Chapter 2.1 --- CVD system --- p.7 / Chapter 2.2 --- Sources and Substrates --- p.7 / Chapter 2.3 --- Growth of A1N nanowires --- p.8 / Chapter 2.4 --- Growth of AlGaN nanowires --- p.9 / Chapter Chapter 3 --- Characterization --- p.11 / Chapter 3.1 --- Scanning Electron Microscopy --- p.11 / Chapter 3.1.1 --- Topographic images by secondary electrons --- p.11 / Chapter 3.1.2 --- Elemental Analysis by Energy Dispersive X-ray --- p.12 / Chapter 3.2 --- Transmission Electron Microscopy --- p.12 / Chapter 3.3 --- X-Ray Diffraction --- p.14 / Chapter 3.4 --- Micro-Raman --- p.15 / Chapter Chapter 4 --- Results and Discussion --- p.18 / Chapter 4.1 --- A1N nano-structures --- p.18 / Chapter 4.1.1 --- A1N nano-leaves grown on silicon substrates --- p.18 / Chapter 4.1.2 --- A1N nanowires grown on silicon substrates --- p.19 / Chapter 4.1.3 --- SiNx nanowires grown on silicon substrates --- p.22 / Chapter 4.1.4 --- A1N nanowires grown on sapphire substrates --- p.26 / Chapter 4.1.5 --- Comparison with the results of other research groups --- p.31 / Chapter 4.2 --- AlGaN nano-structures --- p.33 / Chapter 4.2.1 --- AlGaN nanowires grown on silicon substrates --- p.33 / Chapter 4.2.2 --- Temperature dependence --- p.38 / Chapter 4.2.3 --- The influence of the mass ratio (Ga/Al) in the precursor metal sources --- p.43 / Chapter 4.2.4 --- Substrate effect --- p.46 / Chapter Chapter 5 --- Suggestion of the growth mechanism --- p.51 / Chapter 5.1 --- Growth mechanisms: an introduction --- p.51 / Chapter 5.2 --- The growth mechanisms for our produced samples --- p.57 / Chapter 5.2.1 --- Growth mechanism for A1N nanowires --- p.58 / Chapter 5.2.2 --- Growth mechanism for AlGaN nanowires --- p.61 / Chapter 5.2.3 --- Substrate effect --- p.65 / Chapter Chapter 6 --- Conclusions --- p.71 / Appendix --- p.73

自從 Onnes 于1911 年發現超導現象以來，超導就一直是凝聚態領域非常熱門的一個課題。隨之而來的一個問題是超導在量子尺寸效應的影響下將如何變化。在1959 年，Anderson 提出了一個超導受尺寸影響而消失的判據：當超導體的尺寸足够小以至於超導體費米面附近電子的平均能隙大於超導能隙或與其相當時，超導便被尺寸效應破壞。基於這個判據，超導和費米面附近的電子態密度密切相關。Si(111)表面上生長的鉛島在調製費米面附近的態密度上是一個很好的系統，因為它既可以在垂直方向上通過量子阱態調節，也可以通過水平方向的尺寸限制來調節。另外，相對於其他系綜或者粉末超導體，在Si(111)表面上生長的單個鉛島系統上研究超導排除了諸如尺寸分佈，顆粒間相互耦合以及相位漲落等因素對於超導的影響。 / 在這篇論文的緒論中，我首先簡單介紹了基本的超導知識，如 BCS 理論，Eliashberg 理論以及超導在超導體-絶緣體-正常金屬形成的隧道結上的表現形式。跟著，我重點回顧了之前在系綜超導體以及金屬納米結構中進行的超導尺寸效應研究。對於目前廣泛研究的鉛島系統，我將重點談及最近發現的贗能隙，這對研究鉛島的超導至關重要。 / 在第二章，我簡單介紹了樣品的生長和掃描隧道譜的相關知識。爲了分析鉛島的超導譜，我們用了兩種方法去分析他們。一種是零電壓下電導的方法，另一種是超導譜分析方法。在這章的最後，我詳細介紹了Dynes 方程及去捲積的方法。 / 在第三章，我將介紹我博士學習期間一個非常重要的工作，提高儀器的能量分辨率。通過改造儀器結構，合理的接地，屏蔽射頻噪聲，以及清除電壓源的噪聲，我成功地將能量分辨率從0.9 meV 提高到0.2 meV。在最後我會將儀器改進后的結果與之前的結果儀器與其他組的結果進行比較。 / 在儀器改進之前，我們發現那時的測量結果非常差，由此得出的結論也是不正確的。爲了比較儀器改造的重要性，在第四章，我將簡單介紹儀器改進前的結果。在當時差的條件下，我們探測出對於9ML 厚的鉛島，3.2 K 以上不超導的鉛島尺寸，大約為30 nm²。並且鉛島經歷了一個從強電子聲子耦合到弱電子聲子耦合的轉變。 / 在儀器改進之後，我們不僅糾正了之前在九層鉛島上進行超導研究時的一些結論。此外，也觀察到了由於尺寸變化或者費米面上態密度變化導致超導的細微區別。由於尺寸效應，我們發現在一些小的鉛島上存在一個過渡區。另外，由於八層鉛島費米面上的態密度比九層的高，超導轉變溫度也因此有一個系統性的提高。對於這兩個層數的鉛島，他們的超導轉變溫度都隨尺寸減小受到一個緩慢的抑制。對於非常小的鉛島，我們發現其仍然超導。這和Anderson 判據的預期以及其他實驗結果不一致，激發我們進一步探索是否非晶化的潤濕層參與了這種非常小的鉛島的超導。 / 這些工作，對於全面理解超導的尺寸效應以及態密度影響是非常基本和關鍵的，這也將進一步激發人們在這個領域進行更多的探索。 / Superconductivity has always been a hot topic in the field of condensed matter physics since its discovery by Onnes in 1911. How the superconductivity was affected by size attracted much attention especially after P. W. Anderson proposed a criterion of the breakdown of superconductivity in 1959, where the superconductors will lose their superconductivity when the energy level spacing at Fermi level (E[subscript F]) is comparable to or larger than the superconducting energy gap. As stated in the criterion, the superconductivity correlates greatly with the density of states (DOS) at E[subscript F] within the superconducting gap. The system of individual Pb islands grown on Si(111) provides an ideal platform to modulate the DOS at EF through both the quantum size confinement and the quantum well states (QWS) effects. Moreover, this system excludes the problems of size distribution, couplings among particles and phase fluctuation of the previously studied ensembles of particles. / In my thesis, I first introduce briefly the basic knowledge of superconductivity, such as BCS theory and Eliashberg theory, as well as its behaviors in a normal metal-insulator-superconductor tunneling junction. Then the study of superconductivity by quantum size effect on ensemble superconductors and metallic nanostructures is reviewed. For the widely studied system of Pb islands, I discuss in more detail the recently discovered pseudogap which was important and critical for analyzing the superconductivity. / In chapter 2, the knowledge of sample growth is given and a simple introduction to scanning tunneling spectroscopy is presented. To study the superconductivity spectra of Pb islands, we use two methods to analyze them, one the zero bias conductance (ZBC) method and the other the superconductivity spectrum analysis. In the end of this chapter, Dynes function and deconvolution procedure are introduced in detail. / In chapter 3, I introduce one of my important works in my Phd study, to improve the instrumental energy resolution. By reconstructing the instrumental structure, grounding properly, shielding RF noise, and cleaning the voltage gap source, the instrumental energy resolution has been improved greatly from ~0.9 meV to ~0.2 meV. I compare our current results both with previous results and results from other groups. / Before the instrumental improvement, we find that the measurements were very poor and the conclusion thus obtained were incorrect. To show the importance of the instrumental improvement, I introduce briefly the previous work in chapter 4. Under the poor instrumental condition, we found that the limiting size of superconductivity above 3.2 K was determined to be ~30 nm² for 9 ML thick Pb islands and that Pb island superconductors undergo a change from strong to weak electron-phonon coupling. / After the instrumental improvement, we not only correct some conclusions of the previous studies on superconductivity of 9 ML Pb islands, but also observed the more non-trivial variation of superconductivity from the change of island size or density of state (DOS) at Fermi level (E[subscript F]) by the quantum well states (QWS). A critical regime is observed for small Pb islands. As the DOS of 8 ML Pb islands at E[subscript F] is larger than that of 9 ML Pb islands, the transition temperatures (T[subscript C]) of 8 ML Pb islands hold a systematic difference larger than those of 9 ML Pb islands. The T[subscript C] results for both 8 ML and 9 ML Pb islands follow the same gradual suppression and the ratio 2△(0)/k[subscript B]T[subscript C] remains unchanged by the size effect. Further study indicates that for very small 8 ML and 9 ML Pb islands they are still superconducting, inconsistent with the Anderson criteria and other experimental results. This observation suggests a possible role of wetting layer on superconductivity of these small Pb islands. / This work, I believe, is fundamentally interesting and beneficial to understand deeply the phenomena of superconductivity modulated by size effect and DOS change at E[subscript F] and will inspire more future studies in this field. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liu, Jiepeng = 掃描隧道譜研究Si(111)表面上單個鉛島的超導尺寸效應及態密度影響 / 羅杰鵬. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 136-144). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Liu, Jiepeng = Sao miao sui dao pu yan jiu Si(111) biao mian shang dan ge qian dao de chao dao chi cun xiao ying ji tai mi du ying xiang / Luo Jiepeng. / Chapter 1 --- Superconductivity affected by quantum size effect --- p.2 / Chapter 1.1 --- Overview --- p.3 / Chapter 1.2 --- Basic theories to superconductivity --- p.4 / Chapter 1.2.1 --- BeS theory --- p.5 / Chapter 1.2.2 --- Eliashberg equation --- p.8 / Chapter 1.2.3 --- Superconductivity of S-I-N tunneling junction --- p.10 / Chapter 1.3 --- Size effect of superconductivity for ensemble or powder superconductors --- p.12 / Chapter 1.3.1 --- Anderson criteria --- p.13 / Chapter 1.3.2 --- Size-dependent T[subscript C] for different superconductors --- p.13 / Chapter 1.4 --- Size effect of superconductivity for metallic nanostructures --- p.17 / Chapter 1.4.1 --- Metallic nanostructures --- p.17 / Chapter 1.4.2 --- Quantum well states of metallic nanostructures --- p.18 / Chapter 1.4.3 --- Pb nanostructures on Si(111)-7 x 7 --- p.20 / Chapter 1.5 --- summary --- p.25 / Chapter 2 --- Experimental introductions and data analysis methods --- p.26 / Chapter 2.1 --- Experimental introduction --- p.27 / Chapter 2.1.1 --- Growth of Pb islands --- p.28 / Chapter 2.1.2 --- Substrates effects --- p.32 / Chapter 2.2 --- STS studies of Pb islands --- p.36 / Chapter 2.2.1 --- Basic knowledge of STS --- p.36 / Chapter 2.2.2 --- STS results of Pb islands --- p.40 / Chapter 2.3 --- Data analysis methods --- p.41 / Chapter 2.3.1 --- Zero bias conductance analysis --- p.41 / Chapter 2.3.2 --- Superconductivity spectrum analysis --- p.43 / Chapter 2.4 --- Dynes function fitting --- p.44 / Chapter 2.4.1 --- Dynes function --- p.44 / Chapter 2.4.2 --- Deconvolution --- p.47 / Chapter 2.4.3 --- BCS-like analysis --- p.49 / Chapter 2.5 --- Summary --- p.50 / Chapter 3 --- Instrument improvements --- p.51 / Chapter 3.1 --- Previously existed problems --- p.52 / Chapter 3.2 --- Problem analysis and solutions --- p.54 / Chapter 3.2.1 --- Structure and Preamplifier --- p.54 / Chapter 3.2.2 --- Grounding --- p.56 / Chapter 3.2.3 --- Bias voltage source cleaning --- p.57 / Chapter 3.2.4 --- RF noise shielding --- p.60 / Chapter 3.3 --- Tip drift in perpendicular direction when taking STS --- p.65 / Chapter 3.4 --- Improved results --- p.68 / Chapter 3.4.1 --- Comparisons with previous results --- p.68 / Chapter 3.4.2 --- Comparisons with other groups --- p.69 / Chapter 3.5 --- Summary --- p.72 / Chapter 4 --- Superconductivity of 9 ML thick Pb islands with poor energy resolution --- p.75 / Chapter 4.1 --- STS results --- p.76 / Chapter 4.1.1 --- STS results at large energy scale --- p.76 / Chapter 4.1.2 --- STS results at small energy scale Zero bias conductance analysis --- p.79 / Chapter 4.2.1 --- ZBC results --- p.79 / Chapter 4.2.2 --- Comparisons with theoretical calculations --- p.83 / Chapter 4.3 --- Superconductivity spectrum analysis --- p.85 / Chapter 4.3.1 --- Method to obtain superconductivity spectra --- p.86 / Chapter 4.3.2 --- BCS-like analysis --- p.93 / Chapter 4.4 --- Explanation and possible mechanism --- p.97 / Chapter 4.5 --- Summary --- p.99 / Chapter 5 --- DOS modulated superconductivity with improved energy resolution --- p.101 / Chapter 5.1 --- Introduction --- p.102 / Chapter 5.2 --- Experiments --- p.103 / Chapter 5.3 --- Behaviors of zero bias conductance results --- p.104 / Chapter 5.3.1 --- Power law behavior --- p.104 / Chapter 5.3.2 --- Critical regime and To determination --- p.106 / Chapter 5.4 --- Recheck previous results --- p.112 / Chapter 5.4.1 --- Pseudogap --- p.112 / Chapter 5.4.2 --- Transition temperature --- p.115 / Chapter 5.5 --- DOS modulated superconductivity --- p.121 / Chapter 5.5.1 --- Quantum well states of 8 ML and 9 ML Pb islands --- p.121 / Chapter 5.5.2 --- T[subscript C] behavior on a 8 ML and 9 ML Pb island --- p.123 / Chapter 5.5.3 --- Superconductivity behaviors for a set of 8 ML and 9 ML Pb islands --- p.124 / Chapter 5.5.4 --- Superconductivity of very small Pb islands --- p.129 / Chapter 5.6 --- Summary --- p.130 / Chapter 6 --- Conclusions and outlook --- p.132 / Chapter 6.1 --- Conclusions --- p.133 / Chapter 6.2 --- Outlook --- p.134 / Bibliography --- p.136

Nanophotonics is a fast-growing area of both scientific significance and practical value for applications. Nanophotonics studies the interaction between light and electronic systems in nanomaterials and nanostructures as well as the behavior of light in nanometer scales. It covers many hot topics such as plasmonics, two-dimensional materials, and silicon photonics. Increasing attention is given to the area and nanophotonics is expected to have significant impact on future technology advances. This thesis work focuses on three aspects of nanophotonics. The first aspect is in exploring the nonlocal effect and surface correction for nanometer-length-scale plasmonic structures. Plasmonics is the study of the interaction between electromagnetic fields and free electrons in a metal. It exploits the unique optical properties of metallic nanostructures to enable routing and manipulation of light at the nanoscale, where nonlocal effect becomes important. Here we introduce a new surface hydrodynamic model for plasmon propagation at interfaces, which incorporates both nonlocality and surface contributions. This surface correction is calculated via a discontinuity in the normal component of the electric displacement in conjunction with Feibelman's d-parameters, thus enabling rapid numerical calculation of nanostructures without requiring a full quantum calculation because of its large computational requirement. We examine numerical calculations of surface plasmon polaritons propagation at a single interface structure, and then for a more complex thin-film structures. The second aspect is investigating the third-harmonic generation in thick multilayer graphene. Graphene is the first two-dimensional material to be discovered and has attracted much interest because of its remarkable two-dimensional electronic, optical, mechanical, and thermal properties. Multilayer graphene, can be seen as stacking of monolayer graphene, and it offers an array of properties that are of interest for optical physics and devices. We describe the layer-dependent for third-harmonic generation in thick multilayer graphene on quartz substrate. The third harmonic signal of multilayer graphene exhibits a complex dependence on its layer number showing that the optimal third harmonic signal at 24 layers, in good agreement with two theoretical models. The third aspect is an exploration in silicon photonics of design and demonstration of a differential phase shift keying demodulator based on coherent perfect absorption effect. Silicon photonics is considered a potential future communication system mainly due to its compact footprint, dense integration, and compatibility with mature silicon integrated circuit manufacturing. Differential phase shift keying based system offers advantages, e.g., dispersion tolerance, improved sensitivity, and does not require coherent detection. Coherent perfect absorption uses a ring resonator works for the critical coupling condition at resonance frequency. This work shows a new compact demodulator circuit can be integrated in all optical-system.

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by Leung Kit Sum = 透過X光電子譜研究射頻濺射之銅復合物石英 / 梁潔心. / Thesis submitted in: August 2002. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 77-78). / Text in English; abstracts in English and Chinese. / by Leung Kit Sum = Tou guo X guang dian zi pu yan jiu she pin jian she zhi tong fu he wu shi ying / Liang Jiexin. / Abstract --- p.i / 論文摘要 --- p.iii / Acknowledgement --- p.iv / Table of Content --- p.v / List of Figures --- p.ix / List of Tables --- p.xi / Chapter CHAPTER 1 --- INTRODUCTION / Chapter 1.1 --- Nanoparticles and Nanophase Materials --- p.1 / Chapter 1.2 --- Nonlinear Optical Phenomena and Their Physical Origin --- p.4 / Chapter 1.2.1 --- Dielectric Confinement --- p.6 / Chapter 1.2.2 --- Quantum Confinement --- p.8 / Chapter 1.2.2.1 --- Intraband Transition --- p.9 / Chapter 1.2.2.2 --- Interband Transition --- p.9 / Chapter 1.2.2.3 --- Hot-electron Transition --- p.11 / Chapter 1.3 --- Importance of Optical Nonlinearity --- p.11 / Chapter 1.3.1 --- Self-Phase Modulation --- p.11 / Chapter 1.3.2 --- Self-Focusing/Defocusing --- p.12 / Chapter 1.4 --- Sample Preparation --- p.12 / Chapter 1.4.1 --- Sputtering --- p.13 / Chapter 1.5 --- Characterization of Nanocomposites --- p.15 / Chapter 1.6 --- Aim of the Project --- p.15 / References --- p.17 / Chapter CHAPTER 2 --- INSTRUMENTATION / Chapter 2.1 --- Introduction --- p.20 / Chapter 2.2 --- Sputter Deposition --- p.20 / Chapter 2.2.1 --- Glow Discharge --- p.21 / Chapter 2.2.2 --- Radio-Frequency Sputtering (RF Sputtering) --- p.24 / Chapter 2.2.3 --- Magnetically Enhanced Sputtering --- p.24 / Chapter 2.2.4 --- Instrumentation --- p.25 / Chapter 2.2.4.1 --- Target Assemblies --- p.27 / Chapter 2.2.4.2 --- Shutter --- p.28 / Chapter 2.2.4.3 --- Substrate Holder --- p.28 / Chapter 2.2.4.4 --- Power Supply --- p.28 / Chapter 2.2.5 --- Experimental --- p.29 / Chapter 2.3 --- X-ray Photoelectron Spectroscopy (XPS) --- p.29 / Chapter 2.3.1 --- Instrumentation --- p.31 / Chapter 2.3.2 --- Application to metal nanoclusters composite glass --- p.33 / Chapter 2.3.2.1 --- Compositional Analysis --- p.33 / Chapter 2.3.2.2 --- Depth Profiling --- p.33 / Chapter 2.3.3.3 --- Auger Parameters --- p.33 / Chapter 2.4 --- Transmission Electron Microscopy (TEM) --- p.34 / Chapter 2.4.1 --- Sample Preparation --- p.35 / Chapter 2.4.1.1 --- Sample Thickness Determination --- p.35 / Chapter 2.4.1.2 --- Ion Milling --- p.36 / Chapter 2.4.2 --- Instrumentation --- p.36 / Chapter 2.4.3 --- Contrast and Image Formation --- p.38 / Chapter 2.4.3.1 --- Bright and Dark Field Image --- p.38 / Chapter 2.4.3.2 --- Mass and Thickness Contrast --- p.40 / Chapter 2.4.3.3 --- Diffraction Contrast --- p.40 / References --- p.42 / Chapter CHAPTER 3 --- COMPOSITION AND NANUSTRUCTURE OF COPPER DOPED FUSED SILICA / Chapter 3.1 --- Introduction --- p.44 / Chapter 3.2 --- Experiment --- p.45 / Chapter 3.3 --- Results and Discussion --- p.47 / Chapter 3.3.1 --- Effect of Input RF Power on the Growth of Film --- p.47 / Chapter 3.3.2 --- Theoretical Calculation of Cluster Size by Ratio of Surface to Total Amount of Copper --- p.55 / Chapter 3.3.3 --- TEM Studies of Copper Nanoclusters --- p.57 / Chapter 3.3.4 --- Further Discussion: Effect of Current and Voltage on the Determination of Deposition Rate --- p.60 / Chapter 3.3.5 --- Atomic Distribution and Chemical State of Copper Nanocluster --- p.60 / Chapter 3.3.6 --- Effect of Pressure on the Growth of Film --- p.66 / Chapter 3.3.6.1 --- How Pressure Affects Cluster Growth --- p.70 / Chapter 3.3.7 --- Effect of Deposition time on the Growth of Film --- p.71 / Chapter 3.3.7.1 --- How Film thickness Affects Cluster Growth --- p.75 / Chapter 3.4 --- Summary --- p.75 / References --- p.77 / Chapter Chapter 4 --- CONCLUSION AND FUTURE DIRECTIONS / Chapter 4.1 --- Conclusion --- p.79 / Chapter 4.2 --- Future Directions --- p.79 / Chapter 4.2.1 --- Generation of Active Matrix Nanocomposite --- p.79

At last, a thermal evaporation method that modifies the surface of ZnO nanorods and forms core shell structure is developed, which structure constitutes the photoelectrode for solar energy application. Single crystal ZnO nanorods are uniformly covered by wurtzite polycrystalline CdxZn1-x SySe1-y layer. The band gap of the shell can be systematically tuned from 2.5 to 1.7 eV by varying its composition, as suggested by the optical extinction measured of the samples. The type II band alignment between the ZnO core and the alloy shell enables effective photo-generated charge carrier separation, and the single crystalline ZnO nanorod array provides a direct electrical pathway for the photo-injected electron transport. The nanocable solar cells exhibited short-circuit current ∼0.2 mA/cm 2 and open-circuit voltages of 0.45 V when illuminated with 100 mW/cm 2 simulated AM 1.5 spectrum. / Green emission is observed from the ZnO nanorods synthesized by both methods, which is commonly attributed to the surface defect emission from the nanostructure. We modify surface of the nanorods with SiO 2 and investigate the relation between green emission and the surface defect. However, the surface passivation fails to reduce the green emission significantly, suggesting that surface defects of ZnO are not necessarily responsible for the green emission, but the interior structure quality of the ZnO nanorods decides the luminescence behavior. / In this study, a solution chemistry based method to grow aligned ZnO nanorod arrays on Zn foil is developed at first. Effects of various growth parameters, including the temperature, solution composition and the concentration of individual components on the morphology, structural quality, and properties of the ZnO nanorods are studied. The average diameter of the nanorods in the array can be tuned from ∼20 nm to ∼150 nm by systematically changing the growth conditions. Nanorods with larger diameters are found to be of better structural quality as compared to the smaller diametered ones, as suggested by the cathodoluminescence measurement. Following similar logic, a vapor transport deposition route on controllable fabricating of the ZnO nanorod arrays is investigated. The average diameter of the ZnO nanorods can be tuned from less than 40 nm to larger than submicron, by controlling the fabrication conditions. Larger-diametered nanorods that grow on higher temperature zone are found to possess higher band edge to defect emission ratio. / One dimensional (1D) ZnO nanostructure becomes a research focus in recent years. On the one hand, ZnO itself possesses structural, electrical and optical properties that make it useful for a diverse range of technological applications. On the other hand, semiconductor nanowire owns many advantages, such as superiority in electron transport and its high surface to volume ratio. Aligned ZnO 1D nanostructures on conducting substrates are of special interests, as they are easy to be integrated into devices, directly working as functional unit. / Jiao, Yang. / Adviser: Li Quan. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 107-109). / 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. / Jiao, Yang.

Wang Chengqing. / "November 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

This thesis presents a novel fabrication process to realize high-aspect-ratio, micron- and nano-sized probes and pipettes which can be used for biological applications. The basic fabrication process employs hydrofluoric (HF) acid to etch the outer layer of the end of capillary tubings and optical fibers as previously reported by other researchers. However, we invented a " sacrificial boundary etching" technique that can be used to shape capillary tubings and fibers into sharp micron-sized pipettes or probes with controllable tip angle. The tip profile and the length of its taper can be controlled by the initial height of HF acid inside a glass tube, which is used as a sacrificial material in shaping the tip profile. Our experimental results showed that capillary tubings and optical fibers can be sharpen into tips with angle as small as 2.1° and with tip diameter of ranging from 300 nm to 5 mum (the initial diameter being 125 mum). If the aspect-ratio (A.R.) of a probe is defined as the ratio between the length of its taper distance and the length of its base diameter, the A.R. for our fabricated probe can be as high as 10∼15. We also conducted cell probing experiments by using the fabricated probe. In addition, we performed microinjection of fluid into cells. On the other hand, by using the fabricated probe, an automated Carbon Nanotubes (CNTs) microspotting system was developed for rapid and batch assembly of bulk multi-walled carbon nanotubes (MWNTs) based nanosensors. By combining dielectrophoretic (DEP) and microspotting technique, MWNT bundles were successfully and repeatably manipulated between arrays of micro-fabricated electrodes. This feasible batch manufacturable method will dramatically reduce production costs and production time of nano sensing devices. / Lai Wai Chiu King. / "August 2005." / Adviser: Wen J. Li. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 4064. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 92-101). / 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.

基於局域表面等離子體共振極其敏感于金屬納米結構的尺寸和形貌的特性，貴金屬納米晶體在近些年來受到了研究人員的極大注意。而膠體金屬納米顆粒在共振時表現出極大的光散射和光吸收截面，且存在于金屬表面的電磁場強度也遠遠高於入射光的電磁場強度。膠體顆粒的各種應用已被發掘並廣泛應用於生物醫學領域，比如表面增強拉曼散射、表面增強螢光、基於等離子的傳感及光熱治療等。然而由於金材料的損耗係數大於銀，金納米材料對電磁場的增強效果弱于銀納米材料。傳統的銀納米膠體顆粒的局域表面等離子體共振峰多局限於420~500 nm，而常見的商業雷射器多在500~660 nm範圍內，目前對膠體銀納米顆粒的大小和形狀的可控性研究的報到還很有限，且將銀納米顆粒的共振調控到常用雷射器的波長範圍內對實際的應用有著重大的意義。本篇論文將系統地研究利用光化學方法製備銀納米十面體和相關納米結構，以及他們的等離子體增強效果。 / 首先，我們將介紹各種化學試劑及光源在銀納米顆粒的形成過程中的作用，以及一種能較好的控制銀納米十面體（LSPR：420~660 nm）的大小的方法。我們發現化學試劑和光源對最終納米顆粒的純度和形狀均有影響。比如通過調節硝酸銀和檸檬酸鈉的摩爾比例可以有效的控制被硼氫化鈉還原出來的金屬納米顆粒的晶體結構。465nm的光照能有效地將聚乙烯吡咯烷酮穩定的小金屬銀納米顆粒轉變成納米十面體。如果我們再使用與十面體種子顆粒的LSPR接近的LED作為光源，並用含有大量的金屬銀納米小顆粒溶液做為前驅液，更大的金屬納米十面體顆粒（LSPR：490~590 nm）可以獲得。而另一方面，使用通過離心的方法提純出來的銀十面體作為種子，更大範圍的金屬十面體（LSPR：490~660 nm）可以被生長出來，即使我們只使用了一種光源（500nm LED）。 / 之後，我們研究了銀十面體的光學性質，及它們基於表面增強拉曼散射的低濃度分子探測的應用。相比于其他形狀的金屬納米顆粒，銀納米十面體能得到更強的拉曼信號，這表明銀納米十面體對局域場的增強效果優於其他的顆粒。實驗結果表明，單個金屬納米顆粒的拉曼平均增強係數能達到10⁶。爲了能將銀納米十面體應用於生物傳感和成像領域，我們製備出具有高穩定性和強拉曼信號的表面增強拉曼探針。另一方面，通過表面增強拉曼光譜，銀納米十面體修飾的矽片能靈敏地探測出10⁻⁸ M的4-MBA分子。我們並通過模擬計算的方法證明，在十面體和襯底之間加入介質和導體薄膜能進一步增加其拉曼靈敏度。 / 最後，我們通過光化學方法在襯底上製備出金屬銀納米結構，並得到一些初步的實驗結果。在633nm鐳射的照射下，組裝在玻璃襯底上的小納米顆粒將會轉變由銀納米片組成的納米結構。通過測量，存在于金屬納米結構中的週期只有幾個微米，這也充分的表明通過光化學的方法，我們可以在襯底上製備出由銀納米顆粒組成的任意結構。拉曼光譜可以作為一種實時觀測銀納米結構生長和表面增強拉曼“熱點形成的有效手段。 / Noble-metal nanocrystals have received considerable attention in recent years for their size and shape dependent localized surface Plasmon resonances (LSPR). Various applications based on colloidal nanoparticles, such as surface enhanced Raman scattering (SERS), surface enhanced fluorescence (SEF), plasmonic sensing, photothermal therapy etc., have been broadly explored in the field of biomedicine, because of their extremely large optical scattering and absorption cross sections, as well as giant electric field enhancement on their surface. However, despite its high chemical stability, gold exhibits quite large losses and electric field enhancement is comparatively weaker than silver. Silver nanoparticles synthesized by the traditional technique only cover an LSPR ranged from 420~500 nm. On the other hand, the range of 500~660 nm, which is covered by several easily available commercial laser lines, very limited colloidal silver nanostructures with controllable size and shape have been reported, and ealization of tuning the resonance to longer wavelengths is very important for the practical applications. In this thesis, a systematic study on photochemical synthesis of silver nanodecahedrons (NDs) and related nanostructures, and their plasmonic field enhancements are presented. / First, the roles of chemicals and the light source during the formation of silver nanoparticles have been studied. We have also developed a preparation route for the production size-controlled silver nanodecahedrons (LSPR range 420~660 nm) in high purity. Indeed our experiments indicate that both the chemicals and the light sources can affect the shape and purity of final products. Adjusting the molar ratio between sodium citrate and silver nitrate can help to control the crystal structure following rapid reduction from sodium borohydride. Light from a blue LED (465 nm) can efficiently transform the polyvinylpyrrolidone stabilized small silver nanoparticles into silver NDs through photo excitation. These silver NDs acting as seeds can be re-grown into larger silver NDs with LSPR ranging from 490 nm to 590 nm, upon receiving LED irradiation with emission close to the LSPR of silver ND seeds, which are suspended in a precursor solution containing small silver nanoparticles. With the aid of centrifugation, silver NDs with high purity can be obtained. Furthermore, silver ND with a broad tuning range (LSPR 490~660 nm) can be synthesized from these seeds using irradiation from a 500 nm LED. / Second, the optical properties of silver NDs and their SERS application for sensitive molecular detection are presented. Raman signal obtained from silver NDs show remarkable advantage over noble nanoparticles of other shaped, thus revealing their strong localized field enhancement. Experimental results demonstrate that average enhancement factor from individual silver ND may be as high as 10⁶. In order to explore their application for biosensing and bioimaging, stable silica coated SERS tags based on silver ND producing high Raman intensity have been studied. Our experiment results indicate that 10⁻⁸ M 4-MBA in solution can be detected by silver NDs modified silicon chip through SERS. Simulation result on the geometry of silver ND/silica spacer/gold film/substrate shows that the Raman sensitivity of the NDs modified chip can be further improved with the insertion of a dielectric/conductor film between them. / Finally, we present a photochemical method for the preparation of silver nanostructures preparation with the use of 633 nm laser. Silver nanostructures composed of silver nanoplates could be grown from small silver nanoparticles deposited on a glass substrate. The periodicity of the silver nanostructures is several micrometers, revealing that this photochemical method has the potential for “writing“ silver pattern on a solid substrate. Raman spectroscopy has also been explored for real-time monitoring of silver nanostructure growth and SERS hotspots formation. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lu, Haifei. / "December 2012." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 122-140). / Abstract also in Chinese. / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Chemical synthesis of noble nanoparticles --- p.1 / Chapter 1.1.1 --- Nucleation --- p.4 / Chapter 1.1.2 --- Evolution from Nuclei to Seeds --- p.5 / Chapter 1.1.3 --- Evolution from Seeds to Nanocrystals --- p.9 / Chapter 1.2 --- Theoretical background of localized surface plasmon (LSP) --- p.14 / Chapter 1.2.1 --- Determination of the dielectric constant --- p.15 / Chapter 1.2.2 --- Maxwell equations --- p.20 / Chapter 1.2.3 --- Quasi static approximation --- p.21 / Chapter 1.2.4 --- Gans Theory --- p.22 / Chapter 1.2.5 --- Mie theory --- p.23 / Chapter 1.2.6 --- Numerical methods --- p.25 / Chapter 1.3 --- Structure of this thesis --- p.29 / Chapter Chapter 2. --- Optical properties of noble nanoparticles and their biomedical applications --- p.30 / Chapter 2.1 --- Introduction --- p.30 / Chapter 2.2 --- LSPR of nanoparticles with different shapes and different material composition --- p.30 / Chapter 2.4 --- Local field enhancement of nanoparticles and their effects to Raman and fluorescence --- p.35 / Chapter 2.5 --- Noble nanoparticles for biomedical applications --- p.38 / Chapter 2.5.1 --- Noble nanocrystals for diagnostics --- p.38 / Chapter 2.5.2 --- Noble nanocrystals for cellular and in vivo bioimaging --- p.41 / Chapter 2.5.3 --- Noble metal nanocrystals in medicine --- p.43 / Chapter Chapter 3. --- Photochemical synthesis of size controlled silver nanodecahedrons (NDs) --- p.46 / Chapter 3.1 --- Introduction --- p.46 / Chapter 3.2 --- Seed mediated plasmon driven regrowth of silver nanodecahedrons . --- p.47 / Chapter 3.3 --- Chemical roles of reagents in the process and mechanism for photogrowth of silver nanodecahedrons --- p.55 / Chapter 3.4 --- Light wavelength effect to the regrowth of silver NDs --- p.63 / Chapter 3.5 --- Control on the crystal defects of small silver nanoparticles and effect of precursor to the regrowth of various size silver NDs --- p.67 / Chapter 3.6 --- Summary --- p.77 / Chapter Chapter 4. --- SERS assessment of silver nanodecahedrons and their application for sensitive detection based on SERS --- p.78 / Chapter 4.1 --- Introduction --- p.78 / Chapter 4.2 --- Investigation on SERS of silver NDs and other nanoparticles --- p.79 / Chapter 4.3 --- Silica coated SERS tags with silver NDs as the core --- p.85 / Chapter 4.4 --- Silver nanodecahedrons for biosensing --- p.93 / Chapter 4.5 --- Summary --- p.101 / Chapter Chapter 5. --- Photochemical growth of Plasmonic nanostructures on solid substrate --- p.103 / Chapter 5.1 --- Introduction --- p.103 / Chapter 5.2 --- Experimental --- p.104 / Chapter 5.3 --- Result and discussion --- p.105 / Chapter 5.3.1 --- Photochemical growth of silver nanostructures by laser irradiation through a single slit --- p.105 / Chapter 5.3.2 --- SERS characterization of silver nanostructures --- p.110 / Chapter 5.3.3 --- Observation of photochemical growth of silver nanostructures --- p.112 / Chapter 5.4 --- Summary --- p.115 / Chapter Chapter 6. --- Conclusion and outlook --- p.117 / References --- p.122