Investigations into leakage current variation in titanium dioxide dielectrics
"Initial study of leakage currents in TiO₂ showed that the leakage current varies and can increase significantly with time. The increase is considered a degradation of the material if it is to be used as a dielectric. Because of this, a more complete study of single crystal and polycrystalline TiO₂ material was undertaken. Leakage current studies of SrTiO₃ suggest that ionic motion is the cause of the leakage current variation. It is reasonable to assume that this is also true for TiO₂. For TiO₂ there are several theories as to ionic defect types and energies so a program was written to help plot the concentration of these defects as a function of donor or acceptor dopants using the most commonly referenced models. In order to determine the effect of electric field and temperature on the leakage response, single crystal and various acceptor doped polycrystalline samples were tested under varying conditions. A degrade time was defined as the time it takes the current to reach ten times the minimum value. Repeated experiments at various temperatures show that the degrade time has an exponential senstivity to temperature. For polycrystalline materials, the Schottky model at the grain boundaries worked well for the variation of the minimum current with electric field. Donor doped polycrystalline samples were fabricated but were too conductive to use as dielectrics. A computer simulation was written that modeled the motion of defect ions and simulated the degradation process. Process parameters (mobility, defect structure, etc) were adjusted and the simulation output showed a period of slow current variation followed by a rapid increase in current"--Abstract, page iv.
Materials Science and Engineering
Ph. D. in Ceramic Engineering
University of Missouri--Rolla
xviii, 162 pages
© 2003 Daniel A. Ciardullo, All rights reserved.
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Full-text not available: Request this publication directly from Missouri S&T Library or contact your local library.http://laurel.lso.missouri.edu/record=b5037226~S5
Ciardullo, Daniel A., "Investigations into leakage current variation in titanium dioxide dielectrics" (2003). Doctoral Dissertations. 1468.