My name is Kathryn. I did my mini-project on Light Emitting Diodes, or LEDs for the course ELEN 4301 Introduction to Semiconductor Devices with Prof. Laibowitz. An overview of the LED operation is presented in this slide. The concept is very simple. We have a pn junction, shown in this figure, which is forward biased so that large numbers of majority carrier electrons on the n-side is injected over the reduced potential hill into the p-side. Holes on the p-side are similarly injected into the n-side. The injected carriers recombine. After the recombination process, the energy released is in the form of photons but only in direct semiconductor such as Gallium Nitride. On the other hand, the energy released during the recombination process in indirect semiconductor such as silicon carbide is dissipated as heat. The light emitted can be in ultraviolet, visible, or infrared regions of the spectrum. Specifically, the semiconductor materials used to produce visible LEDs are subject to three
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Light-emitting diode, Total internal reflection, LEDs