Thesis (M.S.)--University of Michigan, 1958.

Three aspects of glow discharges have been studied: glow discharge oscillations, sputtering, and coupling between cathode and anode regions the two most important regions in a glow discharge. Cathode and anode processes are tightly coupled by electron and ion coupling effects. Both electron and ion coupling effects were observed by studying excited Ar atoms in the cathode and anode regions and observing laser-induced space charge variations and the optogalvanic effect. Laser-induced space charge variations in the glow discharge were observed by the change in potential of an electrical probe. This signal, called the optopotential signal, provides useful information about the cathode and anode processes, and may become another useful spectroscopic detection method. Glow discharge oscillations are old phenomena but our mechanistic understanding of the processes involved continues to grow. A mechanism study is important especially now since a new type of sensitive GC detector is being developed based on this phenomenon. A SPAN model of glow discharge oscillation is proposed: source formation, propagation, accumulation, and neutralization of space charges. Electrode coupling couples the neutralization and source formation processes thus completing the feedback loop necessary for some of the observed oscillations to occur. Four modes of oscillations were found. Emission, space potential and current monitoring, and forced oscillations were used to monitor and identify the mechanisms. Studies of cathodic sputtering with gas flow rates up to 2.13 L/min/jet were carried out in an Atomsource sputtering atomizer with Ar as the jet gas and Cu as the cathode sample. These flow rates are 20-fold greater than those normally used and were found to increase net sputtering yield significantly. A fourfold increase in net sputtering yield was observed when the number of jets in use was decreased from six to one, with the gas flow rate and other conditions held constant. Possible explanations for these effects are offered. / Graduation date: 1996

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by Law Siu Wah = 超薄薄膜的應變和記憶效應 / 羅紹華. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Law Siu Wah = Chao bo bo mo de ying bian he ji yi xiao ying / Luo Shaohua. / Acknowledgement --- p.i / Abstract --- p.ii / 論文摘要 --- p.iv / Table of contents --- p.v / List of Figures --- p.viii / List of Tables --- p.xii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Magnetoresistance (MR) --- p.1 / Chapter 1.1.1 --- Colossal magnetoresistance (CMR) in rare-earth manganites --- p.2 / Chapter 1.1.2 --- Double exchange mechanism --- p.3 / Chapter 1.1.3 --- Jahn-Teller effect --- p.6 / Chapter 1.1.4 --- Tolerance factor --- p.8 / Chapter 1.1.5 --- The effect of doping --- p.10 / Chapter 1.2 --- Our motivation --- p.12 / Chapter 1.3 --- Scope of this thesis work --- p.12 / References --- p.14 / Chapter Chapter 2 --- Experimental methods / Chapter 2.1 --- Thin film deposition --- p.16 / Chapter 2.1.1 --- Facing Target Sputtering (FTS) --- p.16 / Chapter 2.1.2 --- Vacuum system --- p.19 / Chapter 2.2 --- Annealing systems --- p.20 / Chapter 2.2.1 --- Oxygen annealing system --- p.20 / Chapter 2.2.2 --- Vaccum annealing system --- p.21 / Chapter 2.3 --- Characterization --- p.22 / Chapter 2.3.1 --- Profilometer --- p.22 / Chapter 2.3.2 --- X-ray diiffraction (XRD) --- p.22 / Chapter 2.3.3 --- Resistance measurement --- p.24 / References --- p.25 / Chapter Chapter 3 --- Expitaxial growth of La0.67Ca0.33MnO3 single layer thin film / Chapter 3.1 --- Fabrication and characteristics of La0.67Ca0.33MnO3 target --- p.26 / Chapter 3.2 --- Substrate materials --- p.31 / Chapter 3.3 --- Epiaxial growth of LCMO thin film --- p.33 / Chapter 3.3.1 --- Deposition conditions --- p.33 / Chapter 3.3.2 --- Deposition procedure --- p.35 / Chapter 3.3.3 --- Oxygen annealing effect --- p.36 / References --- p.41 / Chapter Chapter 4 --- Strain effect in expitaxial growth of La0. 67Ca0 .33MnO3 thin films / Chapter 4.1 --- Introduction --- p.42 / Chapter 4.2 --- Preparation of LCMO ultra-thin film on different substrates --- p.45 / Chapter 4.2.1 --- Sample preparation --- p.45 / Chapter 4.2.2 --- Oxygen annealing treatment --- p.45 / Chapter 4.3 --- Resistance measurement --- p.50 / Chapter 4.3.1 --- Thickness effect --- p.50 / Chapter 4.3.2 --- Strain effect --- p.63 / Chapter 4.4 --- Discussions --- p.68 / References --- p.69 / Chapter Chapter 5 --- Memory effect and thermal effect of ultra-thin La0.67Ca0.33MnO3 films / Chapter 5.1 --- Introduction --- p.71 / Chapter 5.2 --- Sample description and measurement method --- p.72 / Chapter 5.3 --- Memory effect and thermal effect --- p.73 / Chapter 5.4 --- Discussion --- p.77 / References --- p.80 / Chapter Chapter 6 --- Conclusion / Chapter 6.1 --- Conclusion --- p.81 / Chapter 6.2 --- Future work --- p.82

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed January 5, 2010). PDF text: xxiv, 292 p. : ill. (some col.) ; 11 Mb. UMI publication number: AAT 3365710. Includes bibliographical references. Also available in microfilm and microfiche formats.

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published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

The properties of sputter-deposited multilayered superconductors have been studied, including Mo/Ta metallic superlattices and thin films of YBa₂Cu₃O₇₋ₓ. The former have been prepared with the same integer number of atomic planes of Mo and Ta modulating the layered composition. In contrast to behavior observed in other metal-metal superlattices, Mo/Ta exhibits long range structural coherence and metallic resistivity behavior over the entire range of wavelengths down to the monolayer limit. The structural properties of these superlattices are used to explain an anomalous decrease in the c₄₄ elastic stiffness constant previously observed in Mo/Ta for 20 Å ≤ Λ ≤ 50 Å. Superconductivity measurements indicate "universal" T(c) versus ρ behavior in Mo/Ta, and tunneling results show that these superlattices are weakly-coupled BCS superconductors. The second part of this dissertation examines the properties of superconducting thin films of YBa₂Cu₃O₇₋ₓ prepared by dc triode sputtering from metallic targets of Y and Ba₂Cu₃. Post-depression annealing in O₂ is necessary to form the superconducting oxide. Various substrates were used, including sapphire and MgO, both with and without buffer layers of Ag, and SrTiO₃. The buffer layers are used to decrease the interaction of the substrate with the film. The best results occur with films deposited on MgO with a Ag buffer layer, exhibiting T(c) onsets as high as 90 K and zero resistance by 60 K. I find that the crystalline orientation of films deposited on (100) SrTiO₃ are influenced by the substrate, and re-annealing a sample can sometimes improve its superconducting properties. Overall, reproducibility is the biggest problem with this technique, as Ba metal is highly reactive with the environment.

by Li Ping-wah. / Title in Chinese: / Includes bibliographical references / Thesis (M.Ph.)--Chinese University of Hong Kong, 1986