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Thesis
Light extraction efficiency enhancement of gallium antimonide based mid-infrared superlattice light emitting dodes
University of Iowa
Master of Science (MS), University of Iowa
Spring 2018
DOI: 10.17077/etd.006050
Abstract
The versatility of mid-infrared (mid-IR) optoelectronic devices has become an attractive quality for many high-performance technologies, prompting theoretical and experimental research into enhancement techniques for the extraction efficiency of mid-IR superlattice light emitting diodes (SLEDs). Photonics devices and systems operating in the 3 - 5 μm wavelength region have applications in environmental, medical, industrial, and military technologies.
In this work, we develop techniques to improve performance of gallium antimonide (GaSb) based SLEDs operating at the IR wavelength of 3.8 μm since their current overall extraction efficiency equals less than 1.76%. This low percentage of light extraction is mainly due to Snell’s Law and the Fresnel equations. By texturing the surface, the likelihood of meeting the surface within the critical angle increases.
Taking inspiration from methods utilized to improve efficiency of ultraviolet (UV) and visible (VIS) LEDs, the analytical ray-optics modeling of a lenslet microtexture combined with the mid-IR SLED mesa structure was conducted to determine the optimized geometry when varying different aspects, such as the GaSb background absorption, lenslet radius of curvature, substrate thickness, and back contact material.
Next, a micron-scale lenslet fabrication process for the 3.8 μm emission SLED was developed by following a methodology similar to that for gallium nitride (GaN)-based SLEDs. This process includes photolithography to transfer a circular array onto each mesa structure. Once complete a thermal reflow of the photoresist achieves a semisphere-shaped lenslet. The final step includes conducting an inductively coupled plasma reactive ion etch.
Details
- Title: Subtitle
- Light extraction efficiency enhancement of gallium antimonide based mid-infrared superlattice light emitting dodes
- Creators
- Abby Nicole Drača Venable
- Contributors
- Fatima Toor (Advisor)John P Prineas (Committee Member)David R Andersen (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Electrical and Computer Engineering
- Date degree season
- Spring 2018
- Publisher
- University of Iowa
- DOI
- 10.17077/etd.006050
- Number of pages
- ix, 48 pages
- Copyright
- Copyright 2018 Abby Nicole Venable
- Language
- English
- Description illustrations
- illustrations (some color)
- Description bibliographic
- Includes bibliographical references (pages 47-48).
- Academic Unit
- Electrical and Computer Engineering
- Record Identifier
- 9984097078002771
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