1 / 22

New Lamps for Old: How LEDs are Revolutionizing Lighting Applications

New Lamps for Old: How LEDs are Revolutionizing Lighting Applications. New Lamps for Old. Light Emitting Diode. Lighting applications presently consume about 20% of all electricity generated worldwide. Getting Started. What is light? What kind of light can we ‘see’?

latona
Download Presentation

New Lamps for Old: How LEDs are Revolutionizing Lighting Applications

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. New Lamps for Old: How LEDs are Revolutionizing Lighting Applications

  2. New Lamps for Old Light Emitting Diode

  3. Lighting applications presently consume about 20% of all electricity generated worldwide.

  4. Getting Started • What is light? • What kind of light can we ‘see’? • How is light produced? • How does an incandescent light bulb work?

  5. Light Spectrum Infrared Radiation Ultraviolet Radiation Visible Spectrum 400 nm ~ 3.0 eV 700 nm ~ 1.8 eV high energy low energy

  6. red light emitted gold wire contact LED die semiconductor material reflector cup 1/3 mm

  7. Eg > 4 eV Eg < 4 eV Eg = 0 eV metal Eg > 4 eV insulator 0 < Eg < 4 eV semiconductor UV ~ 3.2 eV ~ 1.9 eV IR 350 nm 750 nm The “gap” energy (Eg) is thekey!

  8. Emission of Light from a Semiconductor

  9. Semiconductors Similar shading indicates complementary pairs that preserve the total valence electron count for AZ stoichiometry.

  10. Band Gap and Periodic Properties Element E , eV (  , nm) g C 5.5 (230) Si 1.1 (1100) Ge 0.66 (1900)  -Sn < 0.1 (12,000)

  11. Semiconductors Similar shading indicates complementary pairs that preserve the total valence electron count for AZ stoichiometry.

  12. Band Gap and Periodic Properties Material ( , nm) E , eV  g (1900) Ge 0.66 GaAs (890) 1.42 ZnSe (460) 2.70 CuBr (430) 2.91

  13. N Al P Ge As Ga In LEDs and Color electrons held tightly P Ga electrons held loosely As

  14. N Al P Ge As Ga Green In Ga P Red As LEDs from Red to Green

  15. Solid Solutions A Z A Z A Z A Z A Z A Z 1.0 0.0 0.8 0.2 0.6 0.4 0.4 0.6 0.2 0.8 0.0 1.0

  16. Periodic Properties Review Atomic size As the size of atoms increases, the electrons are held more or less tightly? Electronegativity is defined as the pull or attraction for electrons in a bond. • From left to right across the periodic table, the electronegativity of atoms ______________. • From top to bottom down a group of the periodic table, the electronegativity of atoms ______________. • Arrange the following bonds in order of increasing difference in electronegativity? GaN GaAs GaP

  17. GaPxAs1–x composition GaP0.40As0.60 GaP0.65As0.35 GaP0.85As0.15 GaP1.00As0.00 Ga0.95In0.05N Making Observations and Measurements Measured voltage Color emitted Observations with liquid nitrogen dipping

  18. Acknowledgments Hope College Lawrence University Appleton Area School District NSF-MRSEC Karen Nordell Pearson Arthur Ellis George Lisensky Mike Condren Connie Roop Brian Bartel http://www.mrsec.wisc.edu/nano

More Related