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Proceedings Paper

Study of efficiency-droop mechanism in vertical red light-emitting diodes using electrical-to-optical impulse responses
Author(s): J.-W. Shi; F.-M. Kuo; Che-Wei Lin; Wei Chen; M. L. Lee; L.-J. Yan; J.-K. Sheu
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Paper Abstract

The mechanism responsible for the efficiency droop in AlGaInP based vertically-structured red light-emitting diodes (LEDs) is investigated using dynamic measurement techniques. Short electrical pulses (~100ps) are pumped into this device and the output optical pulses probed using high-speed photo-receiver circuits. From this, the internal carrier dynamic inside the device can be investigated by use of the measured electrical-to-optical (E-O) impulse responses. Results show that the E-O responses measured under different bias currents are all invariant from room temperature to ~100°. This is contrary to most results reported for AlGaInP based red LEDs, which usually exhibit a shortening in the response time and degradation in output power with the increase of ambient temperature. According to these measurement results and the extracted fall-time constants of the E-O impulse responses, the origin of the efficiency droop in our vertical LED structure, which has good heat-sinking, is not due to thermally induced carrier leakage, but rather should be attributed to defect recombination and the saturation of spontaneous recombination processes.

Paper Details

Date Published: 6 February 2012
PDF: 7 pages
Proc. SPIE 8278, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVI, 82781S (6 February 2012); doi: 10.1117/12.906990
Show Author Affiliations
J.-W. Shi, National Central Univ. (Taiwan)
Univ. of California, Santa Barbara (United States)
F.-M. Kuo, National Central Univ. (Taiwan)
Che-Wei Lin, National Central Univ. (Taiwan)
Wei Chen, National Central Univ. (Taiwan)
M. L. Lee, Southern Taiwan Univ. of Technology (Taiwan)
L.-J. Yan, National Cheng-Kung Univ. (Taiwan)
J.-K. Sheu, National Cheng-Kung Univ. (Taiwan)

Published in SPIE Proceedings Vol. 8278:
Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVI
Klaus P. Streubel; Heonsu Jeon; Li-Wei Tu; Norbert Linder, Editor(s)

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