Advanced LED structures, materials, fabrication, lighting and other applications BY: GARETT...
-
Upload
cathleen-ball -
Category
Documents
-
view
219 -
download
3
Transcript of Advanced LED structures, materials, fabrication, lighting and other applications BY: GARETT...
Advanced LED structures, materials, fabrication, lighting and other applications
BY: GARETT HENRIKSEN
5/4/2015
Abstract Light Emitting diodes are a semiconductor light source that emit light when the PN-junction is
activated. This presentation will explain how LEDs are made, the materials that they are made
out of, the structure that makes them what they are, and how the light that they create is used.
LED StructuresSurface emitting
Edge emitting superluminescent diode
Packages◦ Traditional◦ Surface Mount
MaterialsAluminum gallium arsenide
Aluminum gallium indium phosphide
Aluminum gallium nitride
Aluminum nitride
Gallium arsenide
Gallium arsenide phosphide
Gallium phosphide
Indium gallium nitride
Indium gallium phosphide
LEDs can be made up from group III and V elements from the periodic table.
III-Nitride semiconductors(AlN, InN, GaN): Can create LEDs to cover the ultraviolet to the entire visible spectrum.
Fabrication Grown on sapphire, silicon carbide
Process to create layers:◦ Molecular beam epitaxy◦ Metal organic chemical vapor deposition◦ Liquid phase epitaxy
Other ApplicationsOptical fiber applications
Medical diagnostic equipment
Photolithography
Detecting light
Displays◦ 7 segment ◦ Star-burst◦ Dot matrix◦ TV’s
Advantages and Disadvantages Advantages:
More light per watt
Faster switching
LEDs emit light in a certain direction
Internal reflectors
Disadvantages:
Cost
Harder to design
Summary◦ The two types of LEDs are surface and edge emitting. They can packaged traditionally or surfaced
mounted.◦ When a current is applied to the PN-junction then the holes and electrons combine making photons.◦ Many LEDs can be combined to make a display.◦ The materials used come from the III and V groups on the periodic table◦ Crystal layers are formed using liquid phase epitaxy◦ The final epoxy protects the tiny electronics and keeps everything together◦ LEDs for lighting are much more efficient than incandescent or florescent
References http://electroiq.com/blog/2010/07/production-metrology/
http://phostec.eu/downloadcenter/tsf_led.pdf
http://energy.gov/sites/prod/files/2015/02/f19/haugaard_led-materials_sanfrancisco2015.pdf
https://www.energystar.gov/index.cfm?c=lighting.pr_what_are
http://spectrum.ieee.org/semiconductors/optoelectronics/the-leds-dark-secret
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5699639
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6551030
http://www.soraa.com/public/docs/History-of-GaN-LEDs-IEEE-2013.pdf
http://www.radio-electronics.com/info/data/semicond/leds-light-emitting-diodes/structure-fabrication.php
http://www.rp-photonics.com/light_emitting_diodes.html
http://iopscience.iop.org/2043-6262/1/2/025015/pdf/2043-6262_1_2_025015.pdf
http://www.madehow.com/Volume-1/Light-Emitting-Diode-LED.html
http://www.cnet.com/news/appliance-science-how-led-lights-work/
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/leds.html
http://www.ele.uri.edu/~vijay/ELE432_Report_LED.pdf
http://www.tpub.com/neets/tm/110-4.htm
http://iopscience.iop.org/2043-6262/1/2/025015/pdf/2043-6262_1_2_025015.pdf
Key Points1. The two types of LED structures are surface emitting and edge emitting.
2. Electrons and holes combine, the electron loses energy to create a photon.
3. Direct band gaps create the most amount of photons
4. LED’s are taking over house lighting because they are so much more efficient
5. The color of light emitted from an led is determined by the band gap of the semiconductor