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Proceedings Paper

Simplified electro-optical model for device and circuit simulations of light-emitting diodes (LEDs)
Author(s): Abasifreke U Ebong; Evan Downey; Stephen Arthur; Xiana C. Cao; Stephen LeBoeuf; Danielle W Merfeld
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Paper Abstract

In this paper we present the electro-optical model, using Aimspice in conjunction with a resistor network, for evaluating the LED designs for optimum uniform current spreading and efficient light extraction. Since high brightness is a critical factor for solid-state lighting, the ability for LED designs to be scalable is important, and we use the pinwheel design, which is aimed at increasing the p-contact area to aid in uniform current spreading, to demonstrate our model. The pinwheel LED design does not scale up because the percentage current uniformity decreases with device size and bias current. To validate the model the current voltage characteristics curves for the two LED sizes (X and 3X) are matched and the recombination saturation current densities values extracted as 7.8 x 10-8 A/cm2 and 8.6 x 10-9 A/cm2, respectively. The tunneling saturation current densities for smallest LED, X, is two orders of magnitude lower than the larger device (3X). Although the larger the LED the higher the photon generation, only a small fraction of these photons can escape the device. The largest photon density is generated under the p-metal contact, with decreasing generation towards the edge of the mesa. Since the metal is opaque to the photons, there is that tendency for most of the photons in this region to bounce back and forth in the device and finally get absorbed. For the 3X pinwheel LED at 20 mA forward current, the complimentary experimental and calculated results show that only 2.2% of the generated photons can escape the active region and make it to the outside world.

Paper Details

Date Published: 26 January 2004
PDF: 8 pages
Proc. SPIE 5187, Third International Conference on Solid State Lighting, (26 January 2004); doi: 10.1117/12.511885
Show Author Affiliations
Abasifreke U Ebong, GE Global Research Ctr. (United States)
Evan Downey, GE Global Research Ctr. (United States)
Stephen Arthur, GE Global Research Ctr. (United States)
Xiana C. Cao, GE Global Research Ctr. (United States)
Stephen LeBoeuf, GE Global Research Ctr. (United States)
Danielle W Merfeld, GE Global Research Ctr. (United States)

Published in SPIE Proceedings Vol. 5187:
Third International Conference on Solid State Lighting
Ian T. Ferguson; Nadarajah Narendran; Steven P. DenBaars; John C. Carrano, Editor(s)

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