Title page for etd-0728114-145346


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URN etd-0728114-145346
Author Bo-Chao Huang
Author's Email Address d982030009@student.nsysu.edu.tw
Statistics This thesis had been viewed 5095 times. Download 49 times.
Department Physics
Year 2013
Semester 2
Degree Ph.D.
Type of Document
Language English
Title Study of interfacial electronic properties in heterostructures using scanning tunneling spectroscopy
Date of Defense 2014-07-11
Page Count 85
Keyword
  • hetero-interface
  • semiconductor
  • complex oxide
  • cross-sectional scanning tunneling microscopy (XSTM)
  • superconductor
  • Abstract Hetero-interface has been studied for decades due to the unique physical properties through the interfacial boundary condition. The advance of epitaxial growth technique provides a powerful way to manipulate the interfacial layer in atomic scale accuracy. Consequently, numerous novel hetero-structures are discovered. Motivated by the importance of interesting properties at the novel hetero-interfaces, fundamental mechanisms are elucidated in this study. Utilizing cross-sectional scanning tunneling microscopy (XSTM) with samples cleaved in situ in an ultrahigh vacuum chamber. Topics of the thesis report direct investigations of electronic structures across the interfaces in three model heterostructures, including semiconductors, complex oxides, and superconductor systems.
       In the first case across the high-κ/III-V semiconductor interface, the transistor encounters the limitation in size. We demonstrate that the existence of the chemical bonding at the interface is about 0.7nm in thickness. The band offset values are presented to be over 1eV both in conduction and valence band. Secondly, complex oxide heterostructures, the LaAlO3/SrTiO3 is known as a conducting interface between two insulators. The unusual notched structure and the band alignment across the LaAlO3/SrTiO3 interface are directly mapped from STM experiments. In the third case, the detailed investigation of the electronic structures across the interface between the superconductor YBa2Cu3O7-δ and the ferromagnetism La0.7Ca0.3MnO3 is studied. The proximity induced triplet state is demonstrated from the evolution of interfacial electronic properties at the interface. Results also reveal the spatial resolved coherent length between superconductor and ferromagnetism.
       The unique technique of using XSTM to study the heterostructures allows us to
    explore the interesting properties of novel interfacial structures. The fundamental study across the heterointerfaces potentially provides the crucial point for improving the performance of devices.
    Advisory Committee
  • Hong-Duen Yang - chair
  • Liuwen Chang - co-chair
  • Chia-Seng Chang - co-chair
  • Ying-Hao Chu - co-chair
  • Yung-Sung Chen - co-chair
  • Ya-Ping Chiu - advisor
  • Files
  • etd-0728114-145346.pdf
  • Indicate in-campus at 2 year and off-campus access at 2 year.
    Date of Submission 2014-08-28

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