1. By: Garett henriksen 5/4/2015
Advanced LED structures, materials, fabrication, lighting and other applications
By: Garett henriksen
5/4/2015

2. 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.

3. Outline Structures Materials Fabrication Lighting Other Applications
Advantages and Disadvantages

4. LED Structures Surface emitting Edge emitting Packages
superluminescent diode
Packages
Traditional
Surface Mount

9. Materials Aluminum gallium arsenide Aluminum gallium indium phosphide
Aluminum gallium nitride
Aluminum nitride
Gallium arsenide
Gallium arsenide phosphide
Gallium phosphide
Indium gallium nitride
Indium gallium phosphide

10. 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.

11. Fabrication Grown on sapphire, silicon carbide
Process to create layers:
Molecular beam epitaxy
Metal organic chemical vapor deposition
Liquid phase epitaxy

13. Lighting Aviation lighting Automotive headlights Traffic signals
Camera flashes

15. Other Applications Optical fiber applications
Medical diagnostic equipment
Photolithography
Detecting light
Displays
7 segment
Star-burst
Dot matrix
TV’s

16. Advantages and Disadvantages
More light per watt
Faster switching
LEDs emit light in a certain direction
Internal reflectors
Disadvantages:
Cost
Harder to design

17. 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

18. References http://electroiq.com/blog/2010/07/production-metrology/

19. Key Points
The two types of LED structures are surface emitting and edge emitting.
Electrons and holes combine, the electron loses energy to create a photon.
Direct band gaps create the most amount of photons
LED’s are taking over house lighting because they are so much more efficient
The color of light emitted from an led is determined by the band gap of the semiconductor