Browsing by Subject "Chemical Vapor Deposition"
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Item Direct Feedback Control of Gas-Phase Laser-Induced Deposition(1996) Maxwell, J. L.; Pegna, J.; Messia, D.; DeAngelis, D.Three-dimensional laser Chemical vapor deposition (3D-LCVD) or SALD, was used to prototype metallic and ceramic microstructures. Iron, nickel, and steel metal forms were grown from organic and halogen based precursors. Through the simultaneous use of multiple precursors, specific nickel-iron based alloys were produced. By observing the emission spectra during growth, a measure ofthe volumetric growth rate, was obtained. Direct, PID control ofthe process was then possible using the growth rate measurement as real-time feedback. Calibrated infrared photographs of evolving microstructures were taken at various wavelengths, giving a measure of the temperature gradient over the growth zone. While radiation contributes to heat losses at high temperatures, enhanced convection is the dominant heat transfer mechanism due to the small dimensions of the heated area. Enhanced growth rates, induced by convective flow, were also observed. The heat and mass transfer coefficients were determinedfor various processing conditions, and compare well with experimental data. Axi-symmetric rods may also be grown in both the kinetic and transport-limited regimes, and a systematic study of the precursor pressure and deposit temperature during growth yielded distinct growth regimes, influn, ced by the interplay of heat losses and diffusive transport.Item Novel organometallic precursors for the Chemical Vapor Deposition of metal thin films(2010-08) Rivers, Joseph Henry; Jones, Richard A., 1954-; Cowley, Alan H.; Holliday, Bradley J.; Magnus, Philip D.; Ekerdt, John G.With the growing demand for miniaturization of devices and for new materials with useful properties, the use of Chemical Vapor Deposition (CVD) for the manufacture of thin films is receiving growing attention. The synthesis of potentially volatile metal complexes and investigation of their use as CVD precursors is an important part of this process. The research presented addresses several major areas of this process, (i) the identification and synthesis of ligands which can impart volatility to a metal complex, (ii) the synthesis, characterization, and assessment of volatility of metal complexes containing these ligands, and (iii) the full materials characterization of thin films grown with these complexes. The use of trimethylphosphine, bis(trifluoromethyl)pyrazolate, and bis(trifluoromethyl)pyrrolyl ligands have been successfully used to synthesize volatile new complexes of cobalt, rhodium, and nickel, some of which show promise for use as potential CVD precursors.Item Solid Freeform Fabrication at The University of Connecticut(1996) Harrison, Shay; Crocker, James E.; Manzur, Tariq; Marcus, Harris L.Gas phase solid freeform fabrication research at The University of Connecticut focuses on two main procedures, Selective Area Laser Deposition (SALD) and Selective Area Laser Deposition Vapor Infiltration (SALDVI). A SFF research laboratory is under construction at UCONN, with two new operation systems. These systems possess temperature control, data acquisition capabilities, in-situ video monitoring, and the ability to fabricate SALDVI parts up to four inches wide by four inches long. The procurement of a harmonic generating Nd:YAG six watt laser, capable of producing output at 532, 355, and 266 nanometer wavelengths, as well as a coupled effort with the Photonics Center at the University providing laser diodes at a variety of wavelengths, presents the opportunity to explore interactions involved in gas reactions driven by lasers. Investigations of material systems will include ceramic carbides, nitrides, and their composites, as well as metals.