Title page for etd-0810115-203125


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URN etd-0810115-203125
Author Yu-sheng Wang
Author's Email Address No Public.
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Department Physics
Year 2014
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Optoelectronic behaviors of n-ZnO/i-Al2O3/p-Si diodes under high-power-laser illuminations
Date of Defense 2015-07-28
Page Count 65
Keyword
  • Photoconduction
  • pin-diode
  • tunneling
  • tunnel diode
  • ZnO
  • Abstract In this thesis work, pin-diodes made of p-Si/AlOx/c-ZnO were investigated in regards to their photo-responses to high-power Nd:YAG laser of wavelength = 1064nm and that at 532nm via second-harmonic generation, both operated at various optical power levels. The diodes exhibit large leakage current as they were made, suspected to be a combined result of domain-boundary conduction paths within ZnO, as they are a layer of thin films textured along the c-axis in general, followed by tunneling of carriers across the insulating AlOx layer. Such as-fabricated diodes, characteristic leakage disregarded, demonstrated backward-diode behaviors, essentially a manifestation of a tunneling diode in which the carriers tunnel from one side to the other under an external electric field, whether illuminated or not. The sophisticated IV curves are analyzed as related to the abundant defect-related gap states that obscure the expected forbidden voltage regions of tunneling that are characteristic of the energy gaps of the two constituent semiconductors. Attempts were made to infer the basic semiconductor properties, such as the associated hetero-junction heights, Fermi level positions, among others, from quantitative analysis of the IV curves under illuminations or without. The backward diodes were then annealed at various high temperatures, intended to annihilate a part of the inherent defects, and were then characterized in similar procedures. After annealing, the tunneling characteristics of backward diodes diminished, replaced by slightly leaky regular diode or pin-diode characteristics. Very weak sign of photovoltaic response, if any, could be identified. A circuit model is proposed to account for the observed photoconduction behaviors and their correlations with the processes of the device fabrications are discussed.
    Advisory Committee
  • Li-Wei Tu - chair
  • Zhi-xiong liao - co-chair
  • Der-Jun Jang - co-chair
  • Yung-Sung Chen - advisor
  • Files
  • etd-0810115-203125.pdf
  • Indicate in-campus at 5 year and off-campus access at 5 year.
    Date of Submission 2015-09-11

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