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dc.contributor.authorSun, Ruiqi
dc.description135 pages
dc.description.abstractABSTRACT Dielectrics have been extensively investigated in IC technology for capacitor and transistor applications. The discovery of good amorphous thin-film dielectric materials, with high dielectric constants, low dissipation factors and high breakdown fields for charge storage applications has been of great importance. To identify potential new dielectrics, the composition-spread technique and high throughput experimentation have been widely used to explore materials with excellent properties. In this study, the dielectric properties of amorphous composition-spread thin films were studied. The material systems studied in this work includes Bi-Ti-O, Bi-Ta-O, Bi-Zr-O, Bi-Nb-O and the single composition BaTiO3. Films were deposited by RF magnetron co-sputtering. The Bi-Ti-O composition spread was also annealed via laser spike annealing to explore phase formations, which were further analyzed with synchrotron x-ray diffraction. The dielectric properties of amorphous composition-spread thin films were characterized and discussed. In the composition range of 0.5<x<0.7, amorphous Bi-Ti-O exhibits unexpectedly excellent dielectric properties, with a high dielectric constant, r ~ 53, and a dissipation factor as low as tan  = 0.007. The corresponding maximum breakdown field reaches ~1.6 MV/cm, yielding a maximum stored charge per unit area of up to 8 μC/cm2. This indicates the potential of amorphous Bi-Ti-O as a high-performance thin film dielectric material that is compatible with high-performance integrated circuits. With relatively good frequency-independent dielectric constant, low dissipation factor and good maximum stored charge over a range of compositions, amorphous Bi-Ta-O, Bi-Zr-O and Bi-Nb-O might also be considered candidates for use as capacitor materials. However, these three material systems may not be as good as amorphous Bi-Ti-O. The diffraction analysis of LSA-annealed Bi-Ti-O reveals the formation of the metastable pyrochlore Bi2Ti2O7 and Bi2Ti4O11 phase. In the Bi-rich compositions, δ-Bi2O3 and β-Bi2O3 are stabilized with Ti content, while rutile-type TiO2 is found in Ti-rich compositions. The analysis of dielectric performance of BaTiO3 suggests possible ferroelectric behavior. However, the measurements were not strongly definitive and interpretations proposed are tentative.
dc.rightsAttribution 4.0 International
dc.subjectComposition spread
dc.subjectThin films
dc.typedissertation or thesis
dc.description.embargo2023-09-10 Science and Engineering University of Science, Materials Science and Engineering
dc.contributor.chairvan Dover, R. B.
dc.contributor.committeeMemberThompson, Mike

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Except where otherwise noted, this item's license is described as Attribution 4.0 International