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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Electrostatic Coating with Charge-Compensated Ligandless Copper Nanoparticles

Hubbard, Lance Rex January 2016 (has links)
A nonaqueous electroless deposition (ELD) coating process that uses a charge compensator in lieu of a ligand or complexing agent is presented. Si(100) coupons were hydroxylated using a sulfuric acid-hydrogen peroxide mixture (SPM or piranha). The surface was terminated with an amine group by immersion in a 5 mM solution of (3-aminopropyl)-trimethoxysilane (APTMS) in methanol followed by a 150°C anneal. Metal films were deposited by suspending samples in a bath made by dissolving Cu(II) chloride in ethylene glycol, which also served as the reducing agent, and adding 1-butyl-3-methylimidazolium tetrafluoroborate as a charge compensator. Annealing the coupons at 200°C in nitrogen promoted the formation of an electrically conductive thin film. Four-point probe measurements of the films yielded electrical conductivities in the range 10⁶-10⁷ S/m (10-80% of bulk conductivity). Electron microscopy images of the coated substrates showed a layer structure consisting of nanoparticles. The Cu particle core-ion shell complex is attracted to the positively charged amine groups at high pH depositing a thin metal particle film that is both continuous and conformal. With increasing ionic liquid concentration, film morphology changes from conformal films to discrete islands. In the ionic liquid concentration range from 2.0-2.5 mM, the metal films exhibit increased optical absorbance, luminescence and electrical conductivity. The film properties are correlated to interparticle interactions with electron imagery and spectroscopic ellipsometry. Lastly, a thin metal film was deposited that is both continuous and cohesive on the walls and floor of 5-10X aspect ratio trenches and vias.
32

A contemporary approach to expressiveness in the design of digital musical instruments

Dalgleish, Mathew January 2013 (has links)
Digital musical instruments pose a number of unique challenges for designers and performers. These issues stem primarily from the lack of innate physical connection between the performance interface and means of sound generation, for the latter is usually dematerialised. Thus, this relationship must instead be explicitly determined by the designer, and can be essentially any desired. However, many design issues and constraints remain poorly understood, from the nature of control to the provision of performer-instrument feedback. This practice-based research contends that while the digital and acoustic domains are so different as to be fundamentally incompatible, useful antecedents for digital musical instruments can be found in the histories of electronic music. Specifically, it argues that the live electronics of David Tudor are of particular prescience. His home-made circuits offer an electronic music paradigm quite antithetical to both the familiar keyboard interface and the electronic music studios that grew up in the years after World War II, and are seen to embody a number of aspirational qualities. These include performer-instrument interaction more akin to steering rather than fine control, the potential for musical outcomes that are unknown and unknowable in advance, and distinct instrumental character. This leads to the central contribution of this research; the development of a Tudor-inspired conceptual framework that can inform how digital musical instruments are designed, played, and evaluated. To enable more detailed and nuanced discussion, the framework is broken down into a series of sub-themes. These include both design issues such as nuance, plasticity and emergence, and human issues such as experience, expressiveness, skill, learning, and mastery. The notion of sketching in hardware and software is also developed in relation to the rapid iteration of multiple designs. Informed by this framework, seven new digital musical instruments are presented. These instruments are tested from two different perspectives, with the personal experiences of the author supplemented with data from a series of smallscale user studies. Particular emphasis is placed on how the instruments are played, the music they can produce, and their capacity to convey the musical intentions of the performer (i.e. their expressiveness). After the evaluation of the instruments, the Tudorian framework is revisited to form the basis of the conclusions. A number of modifications to the original framework are proposed, from the addition of a dialogical model of performerinstrument interaction, to the situation of digital musical instruments within a wider musical ecology. The thesis then closes with a suggestion of possibilities for future research.
33

Exploring Indian indigenous counselling techniques : evaluating their effectiveness and contribution to counselling psychology

Mundra, Neha January 2013 (has links)
The purpose of this study was to explore whether Indian counsellors and psychotherapists in the UK practice in an indigenous way with their Indian clients. The aim was to find out more information about the different types of Indian indigenous interventions that may currently be used by these professionals. The study also bridges the gap in the literature about the lack of research on the practical uses and applications of Indian indigenous counselling skills in the UK.The study reports data from six face-to-face open-ended semi-structured interviews with Indian counsellors who have been trained in Western psychotherapeutic approaches and have knowledge of Indian psychotherapeutic approaches. The research was analysed using Interpretative Phenomenological Analysis (IPA). Firstly, the analysis concluded the use of several Indian indigenous interventions used by the participants, such as Prekshadhyan which can be used for psychosomatic pain relief, Jain virtue of forgiveness which can be useful for working with sexual abuse, use of spirituality and cultural beliefs for bereavement, and so on. Secondly, the analysis identified some of the most common barriers to therapy (e.g. stigmas and taboos) experienced by Indian clients in the UK, and it provided suggestions on how to overcome these. Finally, the analysis suggested factors that therapists should pay attention to (e.g. client context and use of Indian languages) in order to maximise Indian clients’ engagement in therapy and to minimise their exclusion from it.
34

Chemical reactions at the interfaces of semiconductors and catalysts with solutions: I. Tin-palladium catalysts in electroless copper plating. II. Dissolution of crystalline gallium-arsenide in solutions containing complexing agents.

Pierson, Bruce Gregory. January 1989 (has links)
The concentration of tin and palladium in catalysts used in electroless copper plating have been determined by Rutherford backscattering spectrometry with high energy (2-5) MeV ⁴He⁺. The tin:palladium ratio in the catalyst decreases when exposed to an alkaline solution. X-ray photoelectron spectroscopy has confirmed this result and has shown the palladium in the catalyst is present as palladium metal and the tin is present, probably as an oxidized species, to a depth of about 30 Å. Catalysts for the electroless plating of copper are obtained by the reaction of Pd(II) and Sn(II). The extent of the reaction and the concentrations of the reaction products depend on the solution conditions. Conflicting results obtained in previous investigations of tin-palladium catalysts can be explained on this basis. Single crystals of gallium arsenide (GaAs(100)) were found to dissolve in synthetic lung fluid (Gamble solution). The concentrations of arsenic and gallium in the Gamble solution as well as the arsenic:gallium ratio on the GaAs surface increased continuously as the time of exposure to the Gamble solution increased. X-ray photoelectron spectroscopic studies of the gallium arsenide surface showed that arsenic migrated to the surface and it was oxidized to a species resembling As₂O₃ and finally solubilized by the Gamble solution. The solubility of gallium was governed primarily by the formation of stable complexes with the citrate and phosphate ions in the Gamble solution. Zinc that was present in the single crystals of gallium arsenide also migrated to the surface.
35

The effects of heat treatment on microindentation hardness, abrasion and corrosion resistance of electroless nickel coatings

Schotter, Daniel Keith, 1955- January 1988 (has links)
A study has been carried out to investigate the effects of heat treatment on microindentation hardness, abrasion and corrosion resistance of Electroless Nickel coatings. In particular, a proprietary coating system, NIKLAD 794 has been investigated. Samples of 4130 steel have been plated according to manufacturer's specifications. The plated samples have then been subjected to an array of heat treatment temperatures and times. Post heat treatment tests have been conducted including Taber Abrasion testing, salt fog chamber testing, and Knoop microindentation hardness testing. Results of the individual tests have been compared to determine the effects of heat treatment on, and the interactions between, the parameters examined.
36

Fabricação e caracterização de termopares Cu/CuNixPy obtidos por deposição eletroquímica. / Fabrication and characterization of Cu/CuNixPy thermocouples obtained by electroless deposition.

Saez Parra, Fernando Trevisan 03 July 2008 (has links)
Neste trabalho foram estudadas deposições químicas de ligas CuNixPy e foram fabricados termopares Cu/CuNixPy sobre superfícies de lâminas de silício. Inicialmente, as superfícies foram pré-ativadas em uma solução diluída de ácido fluorídrico contendo PdCl2. Em seguida, foi empregado um banho químico alcalino diluído em água deionizada contendo 15 g/l NiSO4.6H2O; 0,1 a 0,3 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O e 60 g/l Na3C6H5O7.2H2O na temperatura de 80OC sendo que NH4OH foi adicionado até que o pH do banho atingisse o valor de 8,0. Verificamos que a concentração do sal de cobre na solução de deposição afeta substancialmente a quantidade de cobre nos depósitos de CuNixPy. As concentrações planares e as composições dos filmes depositados foram obtidas através da técnica de espectrometria de retroespalhamento de Rutherford (RBS) e a morfologia superficial foi caracterizada através da técnica de microscopia de força atômica (AFM). A solução: 15 g/l NiSO4.6H2O + 0,3 g/l CuSO4.5H2O + 15 g/l Na2HPO2.H2O + 60 g/l Na3C6H5O7.2H2O + NH4OH (pH 8.0) na temperatura de 80OC foi a escolhida na obtenção da liga CuNiP0,5 para a construção de termopares Cu/CuNiP0,5 os quais apresentaram potência termoelétrica de aproximadamente (866) V/oC semelhante aos valores típicos apresentados na literatura para Cu/CuNi. / In this work, it was studied chemical depositions of CuNixPy alloys and it was fabricated Cu/CuNixPy thermocouples onto silicon wafer surfaces. Initially, surfaces were pre-activated in a diluted hydrofluoric acid solution containing PdCl2. Following, it was used a de-ionizedwater- diluted alkaline chemical bath containing 15 g/l NiSO4.6H2O; 0,1-0,3 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O and 60 g/l Na3C6H5O7.2H2O at temperature of 80OC where NH4OH was added until ph was 8.0. The concentration of copper salt in the deposition solution greatly affected the Cu content of the CuNixPy deposits. Areal concentration and composition were measured by Rutherford Backscattering Spectrometry (RBS) and surface morphology was characterized by Atomic Force Microscopy (AFM). The solution: 15 g/l NiSO4.6H2O; 0.3 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O; 60 g/l Na3C6H5O7.2H2O; NH4OH (pH 8.0) at the temperature of 80OC was chosen to obtain the CuNiP0.5 alloy to fabricate Cu/CuNiP0.5 thermocouples with thermoelectric power of about (866) V/oC, which is similar to the typical values reported in literature for Cu/CuNi.
37

Surface properties and solderability behaviors of nickel-phosphorous and nickel-boron deposited by electroless plating. / 化學鍍鎳層的表面性質與焊接能力之關係 / Surface properties and solderability behaviors of nickel-phosphorous and nickel-boron deposited by electroless plating. / Hua xue du nie ceng de biao mian xing zhi yu han jie neng li zhi guan xi

January 2000 (has links)
by Chow Yeung Ming = 化學鍍鎳層的表面性質與焊接能力之關係 / 周洋明. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 62-65). / Text in English; abstracts in English and Chinese. / by Chow Yeung Ming = Hua xue du nie ceng de biao mian xing zhi yu han jie neng li zhi guan xi / Zhou Yangming. / Abstract --- p.i / 論文摘要 --- p.ii / Acknowledgements --- p.iii / Table of Contents --- p.v / List of Figures --- p.viii / List of Tables --- p.ix / Abbreviations --- p.x / Chapter Chapter 1 --- INTRODUCTION / Chapter 1.1 --- Electroless Plating (Autocatalytic Deposition) --- p.1 / Chapter 1.2 --- Electroless Nickel (EN) Plating --- p.2 / Chapter 1.3 --- Types of Electroless Nickel Deposits --- p.2 / Chapter 1.4 --- Properties of Electroless Nickel --- p.5 / Chapter 1.5 --- Applications of Electroless Nickel in Electronic Packaging Industry --- p.7 / Chapter 1.6 --- Importance of Solderability --- p.8 / Chapter 1.7 --- Literature Review of Solderability Studies of Electroless Nickel --- p.9 / Chapter 1.8 --- Motivations & Aims of Studies --- p.10 / Chapter Chapter 2 --- EXPERIMENTAL & INSTRUMENTATION / Chapter 2.1 --- Electroless Nickel Plating --- p.11 / Chapter 2.2 --- Solderability Measurements / Chapter 2.2.1 --- Soldering --- p.13 / Chapter 2.2.2 --- Various test methods for solderability --- p.13 / Chapter 2.2.3 --- Wetting balance method --- p.15 / Chapter 2.2.4 --- Solderability measurements of electroless nickel deposits --- p.17 / Chapter 2.2.5 --- Assessment of wetting curves --- p.19 / Chapter 2.3 --- Surface Oxidation Studies / Chapter 2.3.1 --- Use of X-ray photoelectron spectroscopy (XPS) in surface characterization --- p.19 / Chapter 2.3.2 --- XPS system --- p.22 / Chapter 2.3.3 --- Surface composition of electroless nickel deposits --- p.22 / Chapter 2.3.4 --- Oxide thickness characterization by angle-resolved XPS --- p.25 / Chapter 2.3.5 --- Oxide thickness characterization by XPS depth profiling with low-energy-ion sputtering --- p.28 / Chapter 2.4 --- Surface Morphology Studies / Chapter 2.4.1 --- Surface morphology studies by scanning Auger electron microscopy (SAM) & atomic force microscopy (AFM) --- p.28 / Chapter 2.4.2 --- SAM studies of electroless nickel surfaces --- p.29 / Chapter 2.4.3 --- AFM studies of electroless nickel surfaces --- p.29 / Chapter 2.5 --- Oxide Quality Studies --- p.31 / Chapter Chapter 3 --- RESULTS & DISCUSSIONS / Chapter 3.1 --- Solderability Measurements by the Wetting Balance Method --- p.33 / Chapter 3.2 --- Surface Oxidation Studies / Chapter 3.2.1 --- Surface composition of electroless nickel deposits --- p.36 / Chapter 3.2.2 --- Oxide thickness characterization by angle-resolved XPS --- p.38 / Chapter 3.2.3 --- Oxide thickness characterization by XPS depth profiling with low-energy-ion sputtering --- p.44 / Chapter 3.2.4 --- Conclusion --- p.47 / Chapter 3.3 --- Surface Morphology Studies / Chapter 3.3.1 --- SAM studies of electroless nickel surfaces --- p.49 / Chapter 3.3.2 --- AFM studies of electroless nickel surface --- p.49 / Chapter 3.3.3 --- Conclusion --- p.53 / Chapter 3.4 --- Interpretation of Wetting Kinetics of Electroless Nickel --- p.54 / Chapter Chapter 4 --- CONCLUSIONS & FURTHER STUDIES / Chapter 4.1 --- Conclusions --- p.59 / Chapter 4.2 --- Further Studies --- p.60 / Appendix --- p.61 / References --- p.62
38

Fabricação e caracterização de termopares Cu/CuNixPy obtidos por deposição eletroquímica. / Fabrication and characterization of Cu/CuNixPy thermocouples obtained by electroless deposition.

Fernando Trevisan Saez Parra 03 July 2008 (has links)
Neste trabalho foram estudadas deposições químicas de ligas CuNixPy e foram fabricados termopares Cu/CuNixPy sobre superfícies de lâminas de silício. Inicialmente, as superfícies foram pré-ativadas em uma solução diluída de ácido fluorídrico contendo PdCl2. Em seguida, foi empregado um banho químico alcalino diluído em água deionizada contendo 15 g/l NiSO4.6H2O; 0,1 a 0,3 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O e 60 g/l Na3C6H5O7.2H2O na temperatura de 80OC sendo que NH4OH foi adicionado até que o pH do banho atingisse o valor de 8,0. Verificamos que a concentração do sal de cobre na solução de deposição afeta substancialmente a quantidade de cobre nos depósitos de CuNixPy. As concentrações planares e as composições dos filmes depositados foram obtidas através da técnica de espectrometria de retroespalhamento de Rutherford (RBS) e a morfologia superficial foi caracterizada através da técnica de microscopia de força atômica (AFM). A solução: 15 g/l NiSO4.6H2O + 0,3 g/l CuSO4.5H2O + 15 g/l Na2HPO2.H2O + 60 g/l Na3C6H5O7.2H2O + NH4OH (pH 8.0) na temperatura de 80OC foi a escolhida na obtenção da liga CuNiP0,5 para a construção de termopares Cu/CuNiP0,5 os quais apresentaram potência termoelétrica de aproximadamente (866) V/oC semelhante aos valores típicos apresentados na literatura para Cu/CuNi. / In this work, it was studied chemical depositions of CuNixPy alloys and it was fabricated Cu/CuNixPy thermocouples onto silicon wafer surfaces. Initially, surfaces were pre-activated in a diluted hydrofluoric acid solution containing PdCl2. Following, it was used a de-ionizedwater- diluted alkaline chemical bath containing 15 g/l NiSO4.6H2O; 0,1-0,3 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O and 60 g/l Na3C6H5O7.2H2O at temperature of 80OC where NH4OH was added until ph was 8.0. The concentration of copper salt in the deposition solution greatly affected the Cu content of the CuNixPy deposits. Areal concentration and composition were measured by Rutherford Backscattering Spectrometry (RBS) and surface morphology was characterized by Atomic Force Microscopy (AFM). The solution: 15 g/l NiSO4.6H2O; 0.3 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O; 60 g/l Na3C6H5O7.2H2O; NH4OH (pH 8.0) at the temperature of 80OC was chosen to obtain the CuNiP0.5 alloy to fabricate Cu/CuNiP0.5 thermocouples with thermoelectric power of about (866) V/oC, which is similar to the typical values reported in literature for Cu/CuNi.
39

Fabrication and Characterization of a Palladium/Porous Silicon Layer

Lui, Nicholas Hong 01 September 2013 (has links)
When porous silicon is plated with a catalytic metal, the two materials can act together as a single entity whose electrical properties are sensitive to its environment – the sensing component of an electrochemical gas sensor. Etching pores into silicon is an electrochemical process; and which type of doped silicon used is one of its key parameters. For nearly all reported porous silicon gas sensors, the silicon has been of the p-doped variety – because p-doped porous etching is better understood and the layers that result from it are more predictable – despite n-doped silicon having potentially significant benefits in ease of fabrication and being more conducive to plating by a catalyst. This experiment is an attempt at creating a palladium plated n-doped porous silicon layer, and an examination into what differentiates this fabrication process and the layers that result from the traditional p-doped type. The porous layers to be plated are to be the same and would ideally have properties that are a close approximation to what a functional gas sensor would require. This experiment defined a process that fabricated this “ideal” layer out of N-type, , double polished silicon wafers with a resistance of 20 Ω cm. The wafers were subjected to the anodic etching method with an HF/ethanol mixture as the electrolyte; and only two (of among many) fabrication parameters were varied: HF concentration of the electrolyte and total etching time. We find that a concentration of 12% HF (by volume) and an etching time of 6 hours result in layers most appropriate to carry into plating. The anodization current density is 15 mA cm-2. Deposition of the catalyst, palladium, is done using the electroless method by immersing the porous layer in a .001M PdCl2 aqueous bath. Characterization of this Pd/Porous Silicon layer was done by measuring resistivity by four point probe and imaging through Scanning Electron Microscopy. It was found that layers of a maximum average of 63 ± 6% porosity were created using our fabrication method. There is evidence of palladium deposition, but it is spotty and irregular and is of no improvement despite the n-doping wafer makeup. Resistivity in well-plated regions was measured to be 7-10 Ωcm, while resistivity in regions not well-plated was measured to be 70-140 Ω cm. This is comparable to previous literature values, indicating n-silicon porous silicon can be fabricated and still have potential as a catalytic layer, should metal deposition methods improve.
40

Novel Process and Manufactur of Multi crystalline Solar Cell

Bolisetty, Sreenivasulu January 2009 (has links)
<p>Patterning of multi crystalline silicon Solar cell is prepared with photolithography etching. Electroless plating is used to get metallization of Nickel contacts. SEM analysis of Nickel deposition and measurement of contact resistance for series and shunt resistance is done. To increase the fill factor, the screen printed electrodes are subjected to different firing temperatures there by increasing the efficiency of solar cell. Nickel-silicide formation at the interface between the Silicon and Nickel enhances stability and reduces the contact resistance, resulting in higher energy conversion efficiency.</p><p> </p>

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