17 April 2000 Nonresonant-cavity light-emitting diodes
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Proceedings Volume 3938, Light-Emitting Diodes: Research, Manufacturing, and Applications IV; (2000) https://doi.org/10.1117/12.382829
Event: Symposium on Integrated Optoelectronics, 2000, San Jose, CA, United States
Abstract
The external efficiency of conventional light-emitting diodes (LED's) is limited by total internal reflection at the semiconductor-air interface. For conventional GaAs-based LED's, this results in an extraction efficiency of 2%. In non- resonant cavity (NRC) LED's, this problem is overcome by a combination of internal scattering at a textured top surface and reflection on a back mirror, which increases the probability of escape. Using this approach, we demonstrate external quantum efficiencies of up to 40% without encapsulation of the LED. To gain a more detailed understanding of the out-coupling mechanisms in NRC-LED's, the scattering properties of the textured surface are investigated experimentally. The optimum surface texture is found to randomize the direction of the internally reflected light almost perfectly. In addition, NRC-LED's also enables the enhancement of the external quantum efficiency for small and fast LED's. With efficiencies of about 15%, we demonstrate bitrates of more than 1.3 GBit/s. In order to modify the lambertian output characteristics, we have successfully applied microlenses, allowing 50% coupling efficiency into optical fibers with NA equals 0.5.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Reiner Windisch, Maarten Kuijk, Barundeb Dutta, Alexander Knobloch, Peter Kiesel, Gottfried H. Doehler, Gustaaf Borghs, Paul L. Heremans, "Nonresonant-cavity light-emitting diodes", Proc. SPIE 3938, Light-Emitting Diodes: Research, Manufacturing, and Applications IV, (17 April 2000); doi: 10.1117/12.382829; https://doi.org/10.1117/12.382829
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