Papers by Author: Richard P. Vinci

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Authors: Seung Min Hyun, Walter L. Brown, Richard P. Vinci
Abstract: Thin metal films often play an important role as structural elements or reflective surfaces in MEMS applications. Mechanical properties of the films are important due to their influence on the performance of MEMS devices that involve bending or stretching metal parts. In order to gain a better understanding of the mechanical behavior of thin metal films, we have developed a novel bulge system and measured mechanical properties of aluminum thin films. The thin films were prepared by e-beam evaporation of high purity Al onto 2 or 3mm ×12 mm rectangular silicon nitride membrane windows in silicon frames. N2 gas was used to pressurize and thus bulge the membranes. The bulge height was measured based on changes of capacitance between the membrane and a fixed, closely spaced electrode. This apparatus provides resolution of approximately 50 nm in bulge height at a data acquisition rate of 100/sec and provides strain rates in the membrane up to 10-5/sec. The stability of the apparatus allows stress relaxation measurements to be made to times of many hours. Time dependent elastic modulus changes of 1 m Al films were measured over periods of times under constant stress.
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Authors: M. Topic, Richard P. Vinci, Zakhelumuzi Khumalo, C. Mtshali
Abstract: We investigated two coatings, Pt:Al and Pt3:Al, deposited onto pure Al substrates. After annealing at 500°C for 2 hours in vacuum, the Pt:Al coating became “matt silver” while the Pt3:Al colour was “old gold”. Although the deposited coatings were relatively smooth, rope-and ridge-like morphologies were observed in the annealed Pt:Al and Pt3:Al coatings, respectively. X-ray diffraction analyses revealed the presence of Al21Pt6 and Al2Pt intermetallics in annealed Pt:Al while only the Al2Pt intermetallic phase was observed in the annealed Pt3:Al coatings. RBS spectra showed an increase of coating thickness by four times in the Pt:Al whilst the coating thickness was doubled in the Pt3:Al coatings. The changes to color, surface morphology, and thickness caused by thermal annealing were attributed to the structural characteristics of the most dominant phases.
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Authors: Jeffrey M. Biser, Jason T. Perkins, Hong Wei Li, Helen M. Chan, Richard P. Vinci
Abstract: It has recently been demonstrated that it is possible to produce a pristine surface layer on a lapped sapphire substrate by depositing a thin film of aluminum and subjecting it to an appropriate thermal treatment. This process also shows promise for the fabrication of nanopatterned sapphire by pre-patterning the aluminum metal prior to thermal conversion to sapphire. We have explored two distinct patterning processes: a dual layer photoresist e-beam lithography technique for fabricating arbitrarily shaped aluminum structures, and a novel, non-conventional mask-liftoff method involving nanoporous anodized aluminum oxide, useful for patterning very large scale arrays of sub-micron aluminum dots or posts. Our work is focused on refining the fabrication process and investigating the morphological stability of such metal nanostructures during conversion to sapphire.
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Authors: Richard P. Vinci, T. Bannuru, Seung Min Hyun, Walter L. Brown
Abstract: Pt-IrOx and Au-V2O5 thin films were created by magnetron co-sputtering from multiple targets in an Ar-O2 mixture. Successful Pt-IrOx production required high O2 partial pressure and slow deposition rate followed by post-annealing in pure O2. In contrast, deposition of Au-V2O5 films required relatively low O2 partial pressure, and did not need any post-anneal. These different strategies for forming oxide dispersion strengthened films in a multi-target reactive sputtering configuration are directly related to the thermodynamic characteristics of the two materials systems. The most important characteristics are the low equilibrium oxygen solubility in Pt and Au, and the different degrees of oxygen affinity by Ir and V.
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