21 June 2004 InGaAlP thin film LEDs with high luminous efficiency
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In Thinfilm LEDs, the substrate absorption of the generated light is avoided by a metal reflector between the light emitting layer and the substrate. The light extraction can be further enhanced by buried microreflectors or surface texturing. We demonstrate that the combination of these technologies gives prospects equal or superior to all other known approaches in terms of luminous efficiency and luminance. At a peak wavelength of 617 nm, we have obtained a luminous efficiency of 95.7 lm/W at 20 mA. We further analyze the internal and light extration efficiencies of our LEDs using raytracing simulations as well as a theoretical model for the internal efficiency. This analysis shows quantitatively that the efficient light extraction from InGaAlP thinfilm LEDs becomes more and more difficult when approaching shorter wavelengths.
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Reiner Windisch, Reiner Windisch, Paola Altieri, Paola Altieri, Rainer Butendeich, Rainer Butendeich, Stefan Illek, Stefan Illek, Peter Stauss, Peter Stauss, Wilhelm Stein, Wilhelm Stein, Walter Wegleiter, Walter Wegleiter, Ralph Wirth, Ralph Wirth, Heribert Zull, Heribert Zull, Klaus P. Streubel, Klaus P. Streubel, } "InGaAlP thin film LEDs with high luminous efficiency", Proc. SPIE 5366, Light-Emitting Diodes: Research, Manufacturing, and Applications VIII, (21 June 2004); doi: 10.1117/12.528938; https://doi.org/10.1117/12.528938

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