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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.
81

CHEMICAL VAPOR DEPOSITION OF SAMARIUM COMPOUNDS FOR THE DEVELOPMENT OF THIN FILM OPTICAL SWITCHES BASED ON PHASE TRANSITION MATERIALS.

HILLMAN, PAUL DALLAS. January 1984 (has links)
The physical properties of single crystals of samarium monosulfide exhibit a first order semiconductor-to-metal transition near 6.5 kbar. However, thin films of SmS show only a gradual change in their properties on applying pressure and this renders the technical utilization of the material difficult. Several mechanisms have been proposed as the cause of the smoothing of the transition. They include intrinsic stress, impurities, grain size, improper stoichiometry, and porosity, all of which can be traced to the physical vapor deposition techniques employed in preparing the films. In contrast, chemical vapor deposition was employed in this study because previous work had shown that it could minimize these detrimental modifications in thin films. A new CVD system was tested using a volatile organometallic as the samarium source and reacting it with H₂S. The deposited films contained considerable amounts of oxygen as evidenced by structure analysis, and the origin was traced to the samarium organometallic. The reaction of oxygen-free samarium tricyclopentadienyl with H₂S as well as chemical transport are suggested for deposition of stress-free SmS thin films in future work.
82

A study of cobalt silicide formed by MEVVA implantation.

January 1999 (has links)
by Li Chi Pui. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves [105]-[109]). / Abstracts in English and Chinese. / Abstract / Acknowledgement --- p.Page no / Chapter Chapter 1. --- Introduction / Chapter 1.1 --- Metal silicides --- p.1 / Chapter 1.2 --- Cobalt silicides --- p.3 / Chapter 1.3 --- Ion beam synthesis of metal silicides by metal implantation into silicon --- p.4 / Chapter 1.4 --- Feature of MEVVA implantation --- p.5 / Chapter 1.5 --- Motivation and organisation of this thesis --- p.6 / Chapter Chapter 2. --- Sample Preparation and Characterisation Methods / Chapter 2.1 --- MEVVA implantation --- p.7 / Chapter 2.2 --- Simulation by TRIM --- p.9 / Chapter 2.3 --- Sample preparation --- p.12 / Chapter 2.4 --- Sheet resistivity measurements --- p.14 / Chapter 2.5 --- Rutherford backscattering spectroscopy (RBS) --- p.17 / Chapter 2.6 --- Transmission electron microscopy (TEM) --- p.19 / Chapter 2.6.1 --- Transmission electron microscopy (TEM) sample preparation --- p.21 / Chapter 2.7 --- Atom force microscopy (AFM) and conducting AFM --- p.31 / Chapter Chapter 3. --- Characterisation of As-implanted Samples / Chapter 3.1 --- Experimental details / Chapter 3.1.1 --- Sheet resistance measurements --- p.33 / Chapter 3.1.2 --- Rutherford backscattering spectroscopy (RES) --- p.36 / Chapter 3.1.3 --- Sputtering depth measurements --- p.43 / Chapter 3.1.4 --- Transmission electron microscopy (TEM) --- p.44 / Chapter 3.1.5 --- Spreading resistance profiling (SRP) --- p.61 / Chapter 3.1.6 --- Atom force microscopy (AFM) and conducting AFM --- p.64 / Chapter 3.2 --- Results and discussion --- p.71 / Chapter 3.3 --- Summary --- p.81 / Chapter Chapter 4. --- Characterisation of Annealed Samples / Chapter 4.1 --- Experimental details / Chapter 4.1.1 --- Rutherford backscattering spectroscopy (RBS) --- p.82 / Chapter 4.1.2 --- Transmission electron microscopy (TEM) --- p.87 / Chapter 4.1.3 --- Sheet resistance measurements --- p.98 / Chapter 4.2 --- Summary --- p.101 / Chapter Chapter 5. --- Conclusion --- p.102 / Appendix / Reference
83

An investigation of MEVVA implanted germanium by scanning probe microscopy, ion beam analysis and x-ray diffraction.

January 1999 (has links)
by Lee, Chun-Sing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 98-105). / Abstracts in English and Chinese. / Acknowledgements --- p.2 / Abstract --- p.3 / Table of Contents --- p.7 / List of Figures --- p.10 / List of Tables --- p.13 / Chapter Chapter 1 --- Introduction --- p.14 / Chapter 1.1. --- Ion implantation --- p.14 / Chapter 1.2. --- Scope of the thesis --- p.15 / Chapter Chapter 2 --- Background Theory --- p.17 / Chapter 2.1. --- Ion stopping --- p.17 / Chapter 2.2. --- The energy-loss process --- p.17 / Chapter 2.3. --- Kinematics of binary elastic collision --- p.20 / Chapter 2.4. --- Nuclear and electronic stopping --- p.21 / Chapter 2.5. --- Radiation Damage --- p.22 / Chapter 2.6. --- Spikes --- p.24 / Chapter 2.7. --- Topography of ion bombarded surface --- p.26 / Chapter Chapter 3 --- Equipment Reviews --- p.31 / Chapter 3.1. --- Metal Vapour Vacuum Arc Ion Source Implanter --- p.31 / Chapter 3.2. --- Atomic Force Microscopy --- p.34 / Chapter 3.3. --- Rutherford Backscattering Spectrometry --- p.37 / Chapter 3.4. --- X-ray Diffraction --- p.40 / Chapter Chapter 4 --- Study of Ion Beam Implanted Germanium by Atomic Force Microscopy and Rutherford Backscattering Spectrometry --- p.43 / Chapter 4.1. --- Introduction --- p.43 / Chapter 4.2. --- Experiments --- p.45 / Chapter 4.3. --- Results and discussion --- p.47 / Chapter 4.3.1. --- AFM --- p.47 / Chapter 4.3.2. --- RBS and ion channeling --- p.64 / Chapter 4.4. --- Conclusions --- p.71 / Chapter Chapter 5 --- Ion Beam Synthesised Cobalt Germanide Alloy by Metal Vapour Vacuum Arc Implantation --- p.73 / Chapter 5.1. --- Introduction --- p.73 / Chapter 5.2. --- Experiments --- p.74 / Chapter 5.3. --- Results and discussion --- p.74 / Chapter 5.3.1. --- XRD --- p.74 / Chapter 5.3.2. --- AFM --- p.78 / Chapter 5.3.3. --- RBS and ion channeling --- p.82 / Chapter 5.4. --- Conclusions --- p.87 / Chapter Chapter 6 --- Tip Artifacts in Atomic Force Microscope Imaging of Ion Bombarded Nanostructures on Germanium Surfaces --- p.89 / Chapter 6.1. --- Introduction --- p.89 / Chapter 6.2. --- Experiments --- p.90 / Chapter 6.3. --- Results and discussion --- p.90 / Chapter 6.4. --- Conclusions --- p.95 / Chapter Chapter 7 --- Conclusions --- p.96 / Bibliography --- p.98 / Publications --- p.105
84

Preparation and characterization of granular magnetic cobalt silver thin film.

January 2000 (has links)
by Chiah Man Fat. / Thesis submitted in: September 1999. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 94-97). / Abstracts in English and Chinese. / Acknowledgements --- p.2 / Abstract --- p.3 / Table of Contents --- p.5 / List of Figures --- p.7 / List of Tables --- p.13 / Chapter Chapter 1 --- Introduction --- p.14 / Chapter 1.1. --- Overview --- p.14 / Chapter 1.2. --- Giant Magnetoresistance (GMR) --- p.15 / Chapter 1.3. --- Application of GMR Materials --- p.20 / Chapter 1.4. --- Preparation Methods --- p.22 / Chapter 1.5. --- This Thesis --- p.23 / Chapter Chapter 2 --- Sample Preparation and Experimental Methods --- p.24 / Chapter 2.1. --- MEVVA Ion Source Implanter --- p.24 / Chapter 2.2. --- The Pulsed Filtered Cathodic Arc Co-deposition System --- p.26 / Chapter 2.3. --- Sample Preparation --- p.29 / Chapter 2.3.1 --- Implantation Condition --- p.29 / Chapter 2.3.2 --- Co-deposition Conditions --- p.31 / Chapter 2.4. --- Characterization methods --- p.32 / Chapter 2.4.1 --- Magnetoresistance Measurement --- p.32 / Chapter 2.4.2 --- Atomic Force Microscopy and Magnetic Force Microscopy --- p.34 / Chapter 2.4.3 --- Rutherford Backscattering Spectroscopy (RBS) --- p.37 / Chapter 2.4.4 --- SQUID Magnetometer --- p.38 / Chapter Chapter 3 --- Characterization of Implanted Samples --- p.39 / Chapter 3.1. --- Introduction --- p.39 / Chapter 3.2. --- Results and Discussion --- p.39 / Chapter 3.2.1 --- Ag Film Thickness Dependence --- p.39 / Chapter 3.2.2 --- Dose Dependence --- p.44 / Chapter 3.2.3 --- Extraction Voltage Dependence --- p.46 / Chapter 3.2.4 --- Annealing Temperature Dependence --- p.49 / Chapter 3.2.5 --- Thicker Layer Formation --- p.56 / Chapter 3.2.6 --- AFM and MFM Measurements --- p.58 / Chapter 3.3. --- Summary --- p.64 / Chapter Chapter 4 --- Characterization of Co-deposited Samples --- p.65 / Chapter 4.1. --- Introduction --- p.65 / Chapter 4.2. --- Results and discussion --- p.65 / Chapter 4.2.1 --- RBS Measurement --- p.65 / Chapter 4.2.2 --- Magnetoresistance Measurement --- p.66 / Chapter 4.2.3 --- AFM Measurement --- p.69 / Chapter 4.2.4 --- MFM Measurement --- p.76 / Chapter 4.3. --- Summary --- p.84 / Chapter Chapter 5 --- Conclusion --- p.85 / Chapter 5.1. --- Main Results of This Work --- p.85 / Chapter 5.2. --- Suggestions on Future Works --- p.87 / Appendix --- p.89 / Reference --- p.94 / Publications --- p.97
85

Evolution and Characterization of Partially Stabilized Zirconia (7wt% Y2O3) Thermal Barrier Coatings Deposited by Electron Beam Physical Vapor Deposition

Bernier, Jeremy Scott 17 May 2002 (has links)
Thermal barrier coatings (TBCs) of ZrO2-7wt% Y2O3 were deposited by electron beam physical vapor deposition (EB-PVD) onto stationary flat plates and cylindrical surfaces in a multiple ingot coater. Crystallographic texture, microstructure, and deposition rate were investigated in this thesis. The crystallographic texture of EB-PVD TBCs deposited on stationary flat surfaces has been experimentally determined by comparing pole figure analysis data with actual column growth angle data. It was found that the TBC coating deposited directly above an ingot exhibits <220> single crystal type crystallographic texture. Coatings deposited between and off the centerline of the ingots the exhibited a <311>-type single crystal texture. For coatings deposited in the far corners of the coating chamber either a <111> fiber texture or a <311> single crystal type texture existed. The crystallographic texture of EB-PVD TBCs deposited on cylindrical surfaces was characterized using x-ray diffraction (XRD) at different angular positions on the cylinder substrate. XRD results revealed that crystallographic texture changes with angular position. Changes in crystallographic texture are attributed to the growth direction of the columns and substrate temperature. Growth direction is controlled by the direction of the incoming vapor flux (i.e. vapor incidence angle), in which competition occurs between crystallites growing at different rates. The fastest growing orientation takes over and dominates the texture. Substrate temperature variations throughout the coating chamber resulted in different growth rates and morphology. Morphology differences existed between cylindrical and flat plate surfaces. Flat cross sectional surfaces of the coatings exhibited a dense columnar structure in which the columns grew towards the closest vapor source. Surface features were found to be larger for coatings deposited directly above an ingot than coatings deposited away from the ingots. Morphological differences result from substrate temperature changes within the coating chamber, which influences growth kinetics of the coating. Cylindrical surfaces revealed a columnar structure in which columns grew towards the closest vapor. Porosity of the coating was found to increase when the angular position changed from the bottom of the cylinder. Change in angular position also caused the column diameter to decreases. Morphology changes are attributed to self-shadow effects caused by the surface curvature of the cylinder and vapor incidence angle changes. Overall, the microstructure and crystallographic texture of EB-PVD coatings was found to depend on the position in the coating chamber which was found to influence substrate temperature, growth directions, and shadowing effects. The coating thickness profiles for EB-PVD TBCs deposited on stationary cylinders have been experimentally measured and theoretically modeled using Knudsen's cosine law of emissions. A comparison of the experimental results with the model reveals that the model must to be modified to account for the sticking coefficient as well as a ricochet factor. These results are also discussed in terms of the effects of substrate temperature on the sticking coefficient, the ricochet factor, and coating density.
86

Formation and characterization of cobalt silicide by MEVVA implantation. / CUHK electronic theses & dissertations collection

January 1997 (has links)
by Peng Qicai. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / includes bibliographical references (p. 187-206). / 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.
87

Deformation mechanisms in TiN-based thin film structures

Ma, Lok Wang, Materials Science & Engineering, Faculty of Science, UNSW January 2005 (has links)
The deformation mechanisms and contact response of TiN-based thin films deposited onto a soft substrate using a physical vapour deposition (PVD) technique is still an area of both technological importance and considerable discussion. These coatings are commonly applied to various kinds of steel cutting tools, creating surfaces with enhanced tribological properties. However, no extensive systematic study of the deformation mechanisms in these thin film systems has been performed to date. In the present study, the effect of the coating microstructure, indenter geometry, coating thickness and substrate hardness on the deformation mechanisms in both TiN and TiAlN coatings of varying thickness deposited onto ductile steel substrates has been investigated using a combination of nanoindentation and microstructural analysis, including focused ion beam (FIB) milling and transmission electron microscopy (TEM). Different modes of cracking, such as columnar and transverse cracking, as well as shear steps at the coating/substrate interface, were observed. The microstructure of the TiN coatings was found to be very important in controlling their modes of deformation. Thicker coatings were seen to contain more equiaxed grains, so less columnar shearing occurred and inclined cracks were found to be a more dominant fracture type in the thicker coating. Also, it was found that soft substrates absorbed most of the energy from indentation by plastic deformation. It was found that both the TiN and TiAlN/TiN dual-layer coatings exhibited broadly similar mechanisms of deformation. The epitaxial interface between the TiAlN and TiN in the dual-layer coating did not appear to affect the deformation behaviour. As a further investigation of the overall deformation behaviour for the coating/substrate systems studied, a DualBeam FIB was used to generate three dimensional images of the indented regions which provided additional information on the crack morphology. For the first time, a systematic study of the deformation behaviour of TiN and TiAlN coatings upon indentation has been carried out. FIB milling was demonstrated to be a highly appropriate technique for characterization of the deformation behaviour of these coatings, allowing detailed, high resolution microstructural investigations to be performed in both two and three dimensions.
88

Surface studies of model catalysts using metal atoms and particles on ZnO(0001)-Zn and -O and TiO₂(110) /

Grant, Ann W. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 173-183).
89

Microstructural and microanalytical characterization of laminated (C-SiC) matrix composites fabricated by forced-flow thermal-gradient chemical vapor infiltration (FCVI)

Appiah, Kwadwo Ampofo 05 1900 (has links)
No description available.
90

Growth and characterization of electrodeposited zinc sulphide and chemical vapour atomic layer deposited zinc oxide, sulphide, and oxysulphide thin films.

Sanders, Brian Wayne. Kitai, A.H. Unknown Date (has links)
Thesis (Ph.D.)--McMaster University (Canada), 1991. / Source: Dissertation Abstracts International, Volume: 54-02, Section: B, page: 1040.

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