Title page for etd-0705116-115639


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URN etd-0705116-115639
Author Hung-jie Chen
Author's Email Address kelly931140@gmail.com
Statistics This thesis had been viewed 5566 times. Download 87 times.
Department Physics
Year 2015
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Investigation on the electronic structures of AlO/ZnO superlattices
Date of Defense 2016-07-20
Page Count 69
Keyword
  • AlO
  • ALD
  • superlattice
  • ZnO
  • XPS
  • X-ray photoelectron spectroscopy
  • Abstract This thesis work uses atomic layer deposition (ALD) method to grow AlO/ZnO superlattices on c-oriented sapphire (Al2O3) substrates and then tested their electronic structures by X-ray photoelectron spectroscopy (XPS). The samples were made of alternating ZnO and AlO bilayers with numbers of the ZnO cycles held fixed at 30 while letting the AlO cycles n vary from n = 0, 1, 3, 10, to n = 20. Such a bilayer is repeated for 6 times to make a superlattice. X-ray diffraction analysis indicates that the samples grows epitaxially as a whole for n = 0 and n = 3, and, when epitaxial, the AlO layers also assumes the Wurzite structure. As many factors could all affect the absolute position of an energy level, a meticulous calibration procedure was followed using gold as a standard to which the electron binding energies are referenced. Aanalysis of the core levels of Zn2p, Zn3d, Al2p, O 1s in context of any chemical shits found that introduction of the AlO layer could change the overall nature of chemical bonding within ZnO and AlO. Meanwhile, based on the valence band spectra, presence of the AlO in superlattice forms would also diminished the intrinsic electric polarity of the c-oriented ZnO and force the Fermi level to drift away from the conduction band while also bring into the band gap new energy levels or energy bands. Furthermore, magneto-transport measurements put the carrier concentrations on order of 1020 cm-3 for all samples, contradicting with their semiconducting nature judged from the negative slope of the R(T) curves and the distribution of mid-gap states determined by the XPS measurement of the valence band.
    Advisory Committee
  • Li-Wei Tu - chair
  • Feng-Chuan Chuang - co-chair
  • Sung-Wei Yeh - co-chair
  • Den -Jun Jang - co-chair
  • Quark Yung-Sung Chen - advisor
  • Files
  • etd-0705116-115639.pdf
  • Indicate in-campus at 3 year and off-campus access at 3 year.
    Date of Submission 2016-08-05

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