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M.Sc. / CuInSe2/CdS/ZnO heterojunction solar cells are currently one of the most promising technologies for the production of economically viable energy in the form of electricity. The key component of this thin film solar cell device is the chalcopyrite absorber film. CuInSe2 and its related alloys such as Cu(In,Ga)Se2 have been deposited by a number of techniques, including methods which have been demonstrated to be scalable to mass production volumes. In this study attention was focused on (i) developing a relatively simple deposition technology for the production of chalcopyrite absorber films, (ii) detailed characterization of the semiconductor thin films in terms of the experimental parameters and (iii) fabrication of completed CuInSe2/CdS/ZnO solar cell devices. Metallic precursors comprising of copper and indium were deposited with electron-beam evaporation. The number of elemental layers in the precursor stack as well as the substrate temperature was optimized in order to produce metallic alloys with optimum structural properties. These precursors were subsequently reacted in vacuum to elemental Se vapour or to H2Se/Ar at atmospheric pressure in a separate diffusion reactor. In order to investigate the growth kinetics of the respective processes, the precursors were reacted to the Se in the temperature range between 350°C and 450°C. The structural features (morphology, presence of crystalline phases and bulk compositional properties) of the respective films were compared and correlated against the growth parameters. From this systematic study, optimum growth parameters were determined for the production of completed solar cell devices. / Professor V. Alberts

Thesis advisor: Michael J. Naughton / Geometrically generalized analytical expressions for device transport are derived from first principles for a photovoltaic junction. Subsequently, conventional planar and unconventional coaxial and hemispherical photovoltaic architectures are applied to detail the device physics of the junction based on their respective geometry. For the conventional planar cell, the one-dimensional transport equations governing carrier dynamics are recovered. For the unconventional coaxial and hemispherical junction designs, new multi-dimensional transport equations are revealed. Physical effects such as carrier generation and recombination are compared for each cell architecture, providing insight as to how non-planar junctions may potentially enable greater energy conversion efficiencies. Numerical simulations are performed for arrays of vertically aligned, nanostructured coaxial and hemispherical amorphous silicon solar cells and results are compared to those from simulations performed for the standard planar junction. Results indicate that fundamental physical changes in the spatial dependence of the energy band profile across the intrinsic region of an amorphous silicon p-i-n junction manifest as an increase in recombination current for non-planar photovoltaic architectures. Despite an increase in recombination current, however, the coaxial architecture still appears to be able to surpass the efficiency predicted for the planar geometry, due to the geometry of the junction leading to a decoupling of optics and electronics. / Thesis (PhD) — Boston College, 2012. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

by Siu Wing Hon. / On t.p. T"c", "2", "3", and "7-x" are subscripts following "superconducting" in the title. / Parallel title in Chinese characters. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves [79]-[80]). / Acknowledgement --- p.i / Abstract --- p.ii / Table of Content --- p.iii / Chapter Chapter 1 : --- Introduction / Chapter Chapter 2 : --- Growth of YBCO on Spinel / Chapter 2-1. --- Why Spinel --- p.2-1 / Chapter 2-2. --- Film Deposition Technique --- p.2-3 / Chapter 2-2.1 --- Magnetron Sputtering Technique --- p.2-3 / Chapter 2-2.2 --- Pulsed Laser Ablation --- p.2-4 / Chapter Chapter 3 : --- Composition Analysis by XRF / Chapter 3-1. --- Introduction --- p.3-1 / Chapter 3-2. --- Minimum Penetration Depth of EDX for YBCO film --- p.3-5 / Chapter 3-3. --- Thin Film Method and Thin Film Limit --- p.3-9 / Chapter 3-4. --- XRF Setup --- p.3-14 / Chapter 3-5. --- Calibration --- p.3-14 / Chapter 3-5.1 --- Chemical method --- p.3-18 / Chapter 3-5.2 --- Absorption Factor --- p.3-18 / Chapter 3-5.3 --- Diffusion Rate --- p.3-22 / Chapter 3-5.4 --- Justification of Thin Film Method --- p.3-22 / Chapter 3-5.5 --- Result of Calibration by Chemical Method --- p.3-24 / Chapter 3-5.6 --- Calibration by Rutherford Backscattering --- p.3-28 / Chapter 3-6. --- Discussion on XRF --- p.3-31 / Chapter 3-6.1 --- Effect of diffraction line by substrate on X-ray spectrum --- p.3-31 / Chapter 3-6.2 --- Stability of X-ray power supply and its influence on spectrum --- p.3-34 / Chapter Chapter 4 : --- Structural Analysis and Rapid Thermal Annealing / Chapter 4-1. --- XRD Setup --- p.4-1 / Chapter 4-2. --- XRD Analysis --- p.4-2 / Chapter 4-2.1 --- θ-2θ Scan --- p.4-1 / Chapter 4-2.2 --- Phi Scan --- p.4-3 / Chapter 4-2.3 --- Study of Diffraction Peak --- p.4-9 / Chapter 4-3. --- RTA and its influence on structure --- p.4-11 / Chapter 4-3.1 --- RTA Setup --- p.4-13 / Chapter 4-3.2 --- Structural Improvement by RTA --- p.4-13 / Chapter Chapter 5 : --- Conclusion --- p.5-1 / Chapter Appendix : A. --- Mathematical Derivation of Thin Film Limit / Chapter B. --- Powder Diffraction Patterns of YBCO system / Reference

Bacterial infection is a growing concern in hospital and community settings, where the issue of biofilms is a major problem. Most current methods of preventing microbial attachment and biofilm formation are limited due to application, process or inherent flaws. It was proposed that thin films containing an organometallic element could be deposited using plasma, a quick, clean surface modification technique; to create antimicrobial films which could then be applied to a range of substrates. <br /> Several novel antimicrobial monomer systems were synthesised and characterised based on silver, copper and zinc as the active constituent with phosphines, phosphites, maleimide and a novel Schiff base among the ligand systems. All monomers were found to greatly inhibit the growth of P. aeruginosa and S. aureus in solution and on solid media. Successful monomers were deposited onto suitable substrates (glass, gold, plastics, non-woven polypropylene) using continuous wave and pulse plasma, with the films characterised and low levels of active metal found in analysis using XPS and SIMS. Films were tested against solutions of pathogenic bacteria using a number of traditional and modern microbiological techniques and found to inhibit growth under a range of conditions, potentially due to the synergistic action of metal and ligand on bacterial cells. Effective control of bacteria was exhibited at times varying from 1h to 24h+. Highly volatile compounds were produced which allowed quick deposition of plasma films, which showed excellent activity against bacteria (99.9%+ growth reduction), indicating viability for potential application. All films tested showed no inhibition or toxicity to eukaryotic cells.

Strong size effects in plastic deformation of thin films have been experimentally observed, indicating non-traditional deformation mechanisms. These observations require improved understanding of the behavior of dislocation in small size materials, as they are the primary plastic deformation carrier. Dislocation dynamics (DD) is a computational method that is capable of directly simulating the motion and interaction of dislocations in crystalline materials. This provides a convenient approach to study micro plasticity in thin films. While two-dimensional dislocation dynamics simulation in thin film proved that the size effect fits Hall-Petch equation very well, there are issues related to three-dimensional size effects. In this work, three-dimensional dislocation dynamics simulations are used to study model cooper thin film deformation. Grain boundary is modeled as impenetrable obstacle to dislocation motion in this work. Both tension and cyclic loadings are applied and a wide range of size and geometry of thin films are studied. The results not only compare well with experimentally observed size effects on thin film strength, but also provide many details on dislocation processes in thin films, which could greatly help formulate new mechanisms of dislocation-based plasticity.

by Xianting Zeng. / Publication date from spine. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 165-173). / ABSTRACT --- p.iii / ACKNOWLEDGEMENT --- p.v / TABLE OF CONTENTS --- p.vii / LIST OF FIGURES --- p.x / LIST OF TABLES --- p.xiv / Chapter I. --- Introduction --- p.1 / Chapter 1.1 --- Previous research on magnetoresistance --- p.1 / Chapter 1.2 --- Preparation methods --- p.12 / Chapter 1.3 --- Application prospects and existing problems of GMR materials --- p.15 / Chapter 1.4 --- Main contents in this thesis --- p.17 / Chapter II. --- The facing-target sputtering technique --- p.20 / Chapter 2.1 --- Brief description of FTS method --- p.20 / Chapter 2.2 --- Considerations and studies about the deposition conditions of La-Ca-Mn-O thin films --- p.26 / Chapter 2.2.1 --- Substrate materials --- p.26 / Chapter 2.2.1.1 --- Mismatch of lattice constant --- p.26 / Chapter 2.2.1.2 --- Thermal expansion coefficient --- p.31 / Chapter 2.2.1.3 --- Cleaning and surface treatment --- p.33 / Chapter 2.2.2 --- Substrate temperature --- p.35 / Chapter 2.2.3 --- Discharge pressure and sputtering power --- p.36 / Chapter 2.2.4 --- Oxygen content and critical thickness --- p.36 / Chapter 2.3 --- Fabrication and characteristics of La-Ca-Mn-O target materials --- p.42 / Chapter 3.2.1 --- Fabrication process --- p.42 / Chapter 2.3.2 --- Characterizations --- p.46 / Chapter 2.3.2.1 --- Structural parameters --- p.46 / Chapter 2.3.2.2 --- Electrical and magnetic properties --- p.51 / Chapter III. --- Growth of La-Ca-Mn-O thin films with c-axis orientation --- p.53 / Chapter 3.1 --- Thin film deposition --- p.53 / Chapter 3.2 --- Characterization methods --- p.53 / Chapter 3.2.1 --- XRD --- p.54 / Chapter 3.2.2 --- SEM/EDX --- p.54 / Chapter 3.2.3 --- VSM --- p.57 / Chapter 3.3 --- Results and discussions --- p.58 / Chapter 3.3.1 --- Structures of the films grown on (100) MgO --- p.58 / Chapter 3.3.2 --- Resistance and magnetoresistance --- p.62 / Chapter 3.3.3 --- Annealing effect --- p.69 / Chapter 3.4.3.4 --- Magnetization --- p.71 / Chapter 3.4 --- Conclusion --- p.75 / Chapter IV. --- Epitaxial growth of single crystal LCMO thin films with a-axis orientation --- p.77 / Chapter 4.1 --- Motivation and thin film deposition --- p.77 / Chapter 4.2 --- Characterizations --- p.79 / Chapter 4.2.1 --- DCD/GID --- p.79 / Chapter 4.2.2 --- Laue diffractometry --- p.84 / Chapter 4.3 --- Results and discussions --- p.85 / Chapter 4.4 --- Conclusion --- p.91 / Chapter V. --- Crystal growth mechanisms in the deposition of LCMO thin films --- p.93 / Chapter 5.1 --- Introduction --- p.93 / Chapter 5.2 --- AFM/STM --- p.96 / Chapter 5.3 --- Step-flow growth --- p.100 / Chapter 5.4 --- Roughening growth --- p.107 / Chapter 5.5 --- 3-D growth --- p.111 / Chapter 5.6 --- Conclusion --- p.119 / Chapter VI. --- Anisotropy properties of epitaxial LCMO thin films and colossal low field magnetoresistance --- p.122 / Chapter 6.1 --- Introduction --- p.122 / Chapter 6.2 --- Experiments --- p.124 / Chapter 6.3 --- Results and discussions --- p.125 / Chapter 6.3.1 --- Morphology --- p.125 / Chapter 6.3.2 --- Transport properties --- p.125 / Chapter 6.4 --- Conclusion --- p.134 / Chapter VII. --- Optical response of epitaxial LCMO thin films --- p.135 / Chapter 7.1 --- Introduction --- p.135 / Chapter 7.2 --- Experimental procedures --- p.138 / Chapter 7.2.1 --- Sample preparation --- p.138 / Chapter 7.2.2 --- Measurements of the optical spectra --- p.140 / Chapter 7.2.3 --- Measurements of the optical response --- p.140 / Chapter 7.3 --- Experimental results and discussions --- p.142 / Chapter 7.3.1 --- Optical spectra --- p.142 / Chapter 7.3.2 --- Optical response characteristics --- p.145 / Chapter 7.3.3 --- 1/f noise in LCMO materials --- p.148 / Chapter 7.4 --- Potential applications --- p.154 / Chapter 7.5 --- Conclusion --- p.156 / Chapter VIII. --- Conclusion and further studies --- p.158 / Chapter 8.1 --- Conclusion --- p.158 / Chapter 8.2 --- Further studies --- p.161 / References --- p.165

Yu, Xiaojiang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Abstracts in English and Chinese. / ABSTRACT (ENGLISH) --- p.I / ABSTRACT (CHINESE) --- p.III / ACKNOWLEDGEMENTS --- p.IV / TABLE OF CONTENTS --- p.V / Chapter 1. --- Overview of organic thin-film transistors (OTFTs) --- p.1 / Chapter 1.1 --- Introduction to OTFTs --- p.1 / Chapter 1.2 --- Basic mechanism of OTFTs --- p.4 / Chapter 1.3 --- Applications of OTFTs --- p.6 / Chapter 1.3.1 --- Driving of circuits for electronic papers and LCD --- p.6 / Chapter 1.3.2 --- Light-emitting OTFTs --- p.8 / Chapter 1.3.3 --- Sensing --- p.9 / Chapter 1.4 --- Several key issues --- p.9 / Chapter 1.4.1 --- Mobilities of OTFTs --- p.9 / Chapter 1.4.2 --- Performance of bottom-contact OTFTs --- p.10 / Chapter 1.4.3 --- Stability of OTFTs --- p.11 / Chapter 1.4.4 --- Performance of n-type organic semiconductors --- p.13 / Chapter 1.5 --- Why to study metallophthalocyanine-based OTFTs --- p.14 / Chapter 1.6 --- Objective of this thesis --- p.17 / References --- p.17 / Chapter 2. --- Experimental details for fabrication and characterization of OTFTs --- p.22 / Chapter 2.1 --- Purification of organic semiconductors --- p.22 / Chapter 2.2 --- Preparation of the gate dielectrics for OTFTs --- p.24 / Chapter 2.3 --- Deposition of organic thin films and gold source/drain electrodes --- p.26 / Chapter 2.4 --- Process flow for the fabrication of OTFTs --- p.27 / Chapter 2.5 --- Mobility measurement for the organic thin films --- p.28 / Chapter 2.6 --- Characterization of organic thin films --- p.31 / References --- p.31 / Chapter 3. --- Optimizing the growth of VOPc thin films for high-mobility OTFTs --- p.33 / Chapter 3.1 --- Experimental --- p.33 / Chapter 3.2 --- Results and discussion --- p.34 / Chapter 3.2.1 --- Growth of VOPc thin films on Si02 dielectric --- p.34 / Chapter 3.2.2 --- Growth of VOPc thin films on Ta205 and Al203/Si02 dielectrics --- p.41 / Chapter 3.4 --- Conclusion --- p.44 / References --- p.45 / Chapter 4. --- CuPc/CoPc and VOPc/CoPc p-type/p-type heterostructure OTFTs --- p.46 / Chapter 4.1 --- CuPc/CoPc OTFTs in sandwich configuration --- p.47 / Chapter 4.1.1 --- Experimental --- p.47 / Chapter 4.1.2 --- Results and discussion --- p.48 / Chapter 4.1.3 --- Conclusion --- p.57 / Chapter 4.2 --- VOPc/CoPc OTFTs --- p.57 / Chapter 4.2.1 --- Experimental --- p.57 / Chapter 4.2.2 --- Results and discussion --- p.58 / Chapter 4.2.3 --- Conclusion --- p.63 / References --- p.64 / Chapter 5. --- VOPc/F16CuPc p-type/n-type heterostructure OTFTs --- p.66 / Chapter 5.1 --- Unipolar VOPc/F16CuPc OTFTs --- p.67 / Chapter 5.1.1 --- Experimental --- p.67 / Chapter 5.1.2 --- Results and discussion --- p.69 / Chapter 5.1.3 --- Conclusion --- p.73 / Chapter 5.2 --- VOPc/F16CuPc heterostructure for bottom-contact OTFTs --- p.74 / Chapter 5.2.1 --- Experimental --- p.74 / Chapter 5.2.2 --- Results and discussion --- p.74 / Chapter 5.2.3 --- Conclusion --- p.77 / References --- p.77 / Chapter 6. --- Summary and future work --- p.80 / Summary --- p.80 / Future work --- p.81 / References --- p.83 / Appendix A: Capacitance-voltage (C-V) fitting for ITO/organic junction/AI devices --- p.85 / Appendix B: Can electric-filed influence the growth of organic thin films? --- p.89 / Appendix C: Micro-Raman study on organic thin films --- p.93 / Appendix D: Publications which contributed to this thesis --- p.97

In this thesis, titanium dioxide (TiO2)-based thin film photocatalysts of different morphologies were synthesized and studied for their photoelectrocatalytic and photocatalytic properties. The superhydrophilicity of selected TiO2 films were also assessed. The work started with the synthesis of nanocrystalline TiO2 thin films with minimal porosity. A photoelectrocatalytic study was performed to evaluate the films?? photocurrent response in the presence of various organic compounds. At low concentrations, the amount of photocurrent generated was found to be influenced by the molecular structure of the organic compounds. As the concentration increased, the photocurrent response became dependent on the level of interaction of the organic compounds and their partially degraded intermediates with the TiO2 surface. Highly dispersed platinum (Pt) were added onto TiO2 films by a photo-deposition method, and their photocatalytic and photoelectrocatalytic activities were assessed using a novel thin-layer photo(electrochemical)-catalytic system. The system allowed the photocurrent data that originated from the photoelectrocatalysis process to be collected in the reaction cell, and the amount of organic compound being oxidized to be quantified. The Pt deposits were found to enhance photocatalysis by increasing the photogenerated charge-carriers separation, but conversely they retarded the photoelectrocatalysis process. The next part of the work covered the development of mesoporous TiO2 films via the evaporative-induced self-assembly procedure. The structural characteristics of the films were altered by controlling the relative humidity and temperature during the coating and thermal treatment processes. The effect of key structural parameters, such as film porosity, surface area and crystallinity, on the photoelectrocatalytic activity was investigated. These parameters were found to affect the photoelectrocatalysis because the performance of a catalyst in the photoelectrocatalysis application relies strongly on attributes such as the photocatalyst particles?? interconnectivity and the contact to the conducting substrate. The last part of this thesis demonstrated the effort undertaken to improve the UV-induced superhydrophilic effect of a TiO2 film. A multilayer structure of TiO2 nanoparticles was assembled to create a novel TiO2 film that required no UV-activation to induce a uniform water sheeting across its surface. The novel TiO2 thin film exhibited stable superhydrophilic wetting and anti-fogging behaviors after repetitive cycles of heat and wetting treatment, and this performance was affected by the porosity and surface hydroxyl (-OH) contents.

Graduation date: 2005