Title page for etd-0715108-141932


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URN etd-0715108-141932
Author Chen-Lin Ho
Author's Email Address No Public.
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Department Electrical Engineering
Year 2007
Semester 2
Degree Ph.D.
Type of Document
Language English
Title Micro Structures on Gallium Nitride Light Emitting Diodes for Light Extraction Improvement
Date of Defense 2008-07-04
Page Count 152
Keyword
  • light extraction efficiency
  • microlens
  • ZnO
  • GaN LED
  • SiO2
  • Abstract In recent years, even though the light output of GaN-related LED continues to increase, the brightness is still low compared to conventional lighting systems and it is necessary to further improve the light extraction of LEDs.
    In this study, the characteristics of LPD-SiO2 film and Al/SiO2/GaN MOS diode were investigated in advance of the formation of SiO2 micro structure for improving the oxide quality and controlling the deposition parameters. Temperature-difference method, post-annealing treatment, photochemical treatment, sulfurated treatment and etc. were used for the purposes of better properties of the MOS structure and the LED. To obtain higher light extraction efficiency of GaN LED, hemispherical SiO2 microlens was formed on the conventional and the flip-chip LEDs. The deposition mechanism had been developed to obtain the further improvements on the electrical and optical properties. The influences of epoxy encapsulation on the LEDs without and with microlens were also studied.
    Considering the refractive index of SiO2 is close to that of the epoxy, the enhancements of light extraction efficiency and angular optical distribution of GaN LED by using SiO2 microlens will be degraded after encapsulating. Therefore, we also tried to deposit ZnO film and rod on GaN LED by LPD method to maintain or further enhance the light extraction efficiency of GaN LEDs by the combining the micro structure and the epoxy encapsulation.
    Advisory Committee
  • Kuo-Mei Chen - chair
  • Tsu-Hsin Chang - co-chair
  • Mei-Ying Chang - co-chair
  • Li-Wei Tu - co-chair
  • Ray-Ming Lin - co-chair
  • Yeong-Her Wang - co-chair
  • Ming-Kwei Lee - advisor
  • Files
  • etd-0715108-141932.pdf
  • indicate in-campus access in a year and off_campus not accessible
    Date of Submission 2008-07-15

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