Title page for etd-0606116-102125


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URN etd-0606116-102125
Author Chung-hao Yu
Author's Email Address No Public.
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Department Materials and Optoelectronic Science
Year 2015
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Phase change and coalescence behavior of the particles during pulsed laser ablation of Si3N4 in vacuum and TEOS
Date of Defense 2016-06-21
Page Count 63
Keyword
  • pulsed laser ablation parameter
  • nonstoichiometry
  • silicon nitride
  • defect
  • shape
  • Abstract This research deals with phase change and coalescence behavior of the particles
    produced by pulsed laser ablation (PLA) of Si3N4 (α>>β) polycrystal in vacuum and
    tetraethyl orthosilicate (TEOS) for X-ray diffraction, electron microscopy and optical
    spectroscopy characterizations. The sample produced by PLA of Si3N4 in vacuum under
    free run mode and collected with a C-coated collodion film consists mainly of spherical
    particulates of C-O doped Si with diamond-type structure having 30-200 nm diameter,
    faulted by ~{111} vicinal planes and commonly encapsulated with an amorphous Si or
    SiO2 film as a core-shell structure. As for the sample produced by PLA in vacuum under
    Q-switch mode, it contains mainly C-O doped α-Si3N4-x particulates with spherical shape
    when formed by a solidification route or elongated as whiskers via VLS or VS mechanism.
    The spherical ones have well-developed (01-11) and (0001) faces for mutual coalescence
    to leave misfit dislocations and other more complicated defects despite the surrounding
    amorphous silica phase. The whiskers showed extending growth along <5-1-40> to form
    {10-10} and {12-30} prism faces and (0001) basal face despite the thin (ca. 1 nm)
    amorphous silica coverage and defect-free interior. N2 purging during PLA in vacuum
    under Q-switch mode, effectively raised the N/Si atomic ratio up to ca. 1.2 for the
    resultant α-Si3N4-x whiskers which showed extending growth along <11-20> or <10-10>
    direction to develop the prism faces {10-10}, {11-20}, {12-30} and {5-1-40} as well as the
    (0001) basal face, pyramidal edge, (0001) stacking fault and vacancy clusters due to CO
    dopant. By contrast, PLA of Si3N4 in TEOS under free run mode always produced
    amorphous Si-O-C phase in the form of coalesced particles possibly with medium
    range order and/or atom clusters yet to be clarified. The above substances showed
    characteristic UV-visible absorbance and Raman-PL-XPS bands more or less modified
    by the dopant and internal stress effect.
    Advisory Committee
  • C.N. Huang - chair
  • Shuei-Yuan Chen - co-chair
  • P. Shen - advisor
  • Files
  • etd-0606116-102125.pdf
  • Indicate in-campus at 5 year and off-campus access at 5 year.
    Date of Submission 2016-07-06

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