Title page for etd-0228112-154543


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URN etd-0228112-154543
Author Chung-ho Kao
Author's Email Address No Public.
Statistics This thesis had been viewed 5343 times. Download 1395 times.
Department Materials and Optoelectronic Science
Year 2011
Semester 2
Degree Ph.D.
Type of Document
Language English
Title Epitaxial Growth of TiO2 Thin Film on NaCl Substrate by Oxidation of TiO Thin Film
Date of Defense 2012-02-24
Page Count 89
Keyword
  • TiO2
  • TiO
  • NaCl
  • Sputtering
  • Thin Films
  • Transmission Electron Microscopy (TEM)
  • Abstract Ti thin films were deposited by a radio frequency ion-beam sputtering system. Deposition resulted from sputtering a Ti target (99.995%) with an Ar ion beam. Epitaxial TiO thin films with different orientations, which came from oxidizing Ti thin films, were prepared on single-crystal NaCl substrate. The formation of epitaxial TiO2 thin films (anatase or rutile phase) by oxidation of epitaxial TiO thin films was investigated. The composition, microstructure, and orientation relationships between interfaces were analyzed by TEM and Fourier transformation in the present report.
    Epitaxial TiO thin films with different orientations were prepared on single-crystal NaCl substrate in the present study. The formation of epitaxial TiO2 thin films (anatase or rutile) by oxidation of epitaxial TiO thin films, which were first grown on different NaCl surfaces, was investigated. The composition, microstructure, and orientation relationships between interfaces were analyzed by TEM and Fourier transformation in this report. The TiO to anatase phase transformation has been studied by transmission electron microscopy in this Article. It is shown that prior formation of TiO from Ti film can induce the formation of anatase by thermal oxidation in air, otherwise only rutile is formed. Ti film deposited on the NaCl (001) surface is induced to form epitaxial TiO film by thermal oxidation in air. Further thermal oxidation in air partially transformed TiO into anatase (A) with a parallel orientation relationship of {200}A // {200}TiO. Detailed analysis of the lattice fringes image of the specimen reveals the presence of very high density of misfit dislocations. The TiO to anatase transformation is reversible as further annealing in a vacuum can turn the anatase back into TiO and eliminates the misfit dislocations. The transformation is analyzed in terms of the crystal structure, orientation relationship, and the dislocation distribution, which show that the TiO to anatase transformation is due to the close similarity between their structures. (Chapter 1)
    The anatase TiO2 (001) surface was shown to have superior photoreactivity. Epitaxial anatase (001) films used to be grown on single-crystal SrTiO3 and LaAlO3 substrates. It is shown in this report that these films can be grown also on the NaCl substrate, which is much cheaper and easily prepared. Epitaxial TiO (001) films were first grown on the NaCl (001) substrate. By testing the TiO-to-anatase transformation over temperature and time ranges, an epitaxial anatase (001) film was prepared by simple thermal oxidation in air. The formation of a single-variant anatase (001) film instead of a multiple-variant film is discussed in this report. (Chapter 2)
    An epitaxial rutile (100) thin film has been grown on NaCl substrate instead of other more expensive substrates. An epitaxial TiO (111) thin film with minor Ti phase was first deposited on the NaCl (111) surface by thermal evaporation. It was then transformed into the epitaxial rutile (100) thin film by subsequent thermal oxidation in air. TEM was used to analyze the phases and the orientation relationship. Our previous result showed that an epitaxial anatase (001) film was formed on the NaCl (001) surface in a similar process. The substrate-dependent formation of different TiO2 phase is also discussed in terms of the mismatch of the interfaces. (Chapter 3)
    Advisory Committee
  • Pouyan Shen - chair
  • Ming-chi Chou - co-chair
  • Liuwen Chang - co-chair
  • Hsing-lu Huang - co-chair
  • Dershin Gan - advisor
  • Files
  • etd-0228112-154543.pdf
  • Indicate in-campus at 1 year and off-campus access at 1 year.
    Date of Submission 2012-02-28

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