12.LEDs

12.LEDs - 1 LEDs LEDs Sections 8.1, 8.2, 3.2 of course...

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Unformatted text preview: 1 LEDs LEDs Sections 8.1, 8.2, 3.2 of course text: 1. Voltage efficiency 2. Current efficiency 3. Heterojunctions 4. Recombination 2 Electrical Electrical-- to to-- optical energy conversion optical energy conversion p n 3 Choosing the semiconductor Choosing the semiconductor Indirect- or direct-bandgap material ? 4 GaP GaP is indirect ! is indirect ! How can this work? 5 Spectrum of emitted light Spectrum of emitted light m r * is the reduced effective mass. Use the joint dispersion relation to get the joint DOS. 6 Voltage efficiency: choosing the Voltage efficiency: choosing the colour colour + kT/2 7 Materials for high Materials for high-- brightness brightness LEDs LEDs Why is lattice matching important ? 8 Examples of Examples of colour colour lighting lighting EFS: 18 million LEDs in New York city EFS: Regensburg bridge 9 Current efficiency: choosing the structure Current efficiency: choosing the structure Homojunction Heterojunction For high-brightness LEDs it is necessary to concentrate the recombination into a small volume....
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This note was uploaded on 11/10/2010 for the course EECE 480 taught by Professor David during the Fall '09 term at UBC.

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12.LEDs - 1 LEDs LEDs Sections 8.1, 8.2, 3.2 of course...

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