Paper
21 April 2008 Analysis of the emission characteristics of photonic crystal LEDs
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Abstract
Photonic crystals are known to enhance the extraction efficiency of LEDs and simultaneously shaping the emission pattern. In order to determine the radiation pattern we developed a model based on coupled mode theory that takes into account the lattice pattern, etch depth and the mode distribution. From a basic geometrical consideration a fundamental limit for the directionality is predicted. The calculations fit well to experimental data obtained from green InGaN LEDs incorporating a hexagonal PhC revealing a maximum directionality of 31% within 30°. Additional FDTD simulations were performed for determining quantitatively the extraction efficiency of PhC LEDs compared to LEDs with a roughened surface. Despite its lower overall extraction efficiency, the PhC LED outperforms a standard LED with surface roughening within an acceptance angle of 34° due to the higher directionality of the extracted light.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ch. Wiesmann, K. Bergenek, N. Linder, and U. T. Schwarz "Analysis of the emission characteristics of photonic crystal LEDs", Proc. SPIE 6989, Photonic Crystal Materials and Devices VIII, 69890L (21 April 2008); https://doi.org/10.1117/12.780572
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Cited by 10 scholarly publications.
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KEYWORDS
Light emitting diodes

Diffraction

Finite-difference time-domain method

Photonic crystals

Indium gallium nitride

Refractive index

Semiconductors

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