Light Emitting Diodes (LEDs)

Light Emitting Diodes (LEDs) - Light Emitting Diodes (LEDs)...

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Light Emitting Diodes (LEDs) ELEN 4301 Introduction to Semiconductor Devices Prof. Laibowitz Kathryn Ran Chang
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Overview of the LED Operation Forward bias a p-n junction diode in a direct semiconductor Electrons injected from n-side recombine with holes injected from p-side As a result of the band-to-band recombination, energy is released in the form of photon Emitted radiation can be in ultraviolet, visible, or infrared regions of the spectrum
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Visible LED Materials The semiconductor materials used to produce visible LEDs are subject to three requirements: The semiconductor should be direct With a band gap energy between 1.77 eV and 3.10 eV Be able to form pn junction diode Thus, semiconductor alloys are used to produce commercially available LEDs But no elemental or compound semiconductors meet the 3 requirements
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LED Packaging and Photon Extraction Three mechanisms reduce the amount of emitted photons: Absorption within the LED material
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This note was uploaded on 02/28/2012 for the course EE 4301 taught by Professor Laibowitz during the Spring '10 term at Columbia.

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Light Emitting Diodes (LEDs) - Light Emitting Diodes (LEDs)...

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