Study of efficiency-droop mechanism in vertical red light-emitting diodes using electrical-to-optical impulse responses

J.-W. Shi; F.-M. Kuo; Che-Wei Lin; Wei Chen; M. L. Lee; L.-J. Yan; J.-K. Sheu

doi:10.1117/12.906990

6 February 2012 Study of efficiency-droop mechanism in vertical red light-emitting diodes using electrical-to-optical impulse responses

J.-W. Shi, F.-M. Kuo, Che-Wei Lin, Wei Chen, M. L. Lee, L.-J. Yan, J.-K. Sheu

Author Affiliations +

Proceedings Volume 8278, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVI; 82781S (2012) https://doi.org/10.1117/12.906990
Event: SPIE OPTO, 2012, San Francisco, California, United States

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.

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J.-W. Shi, F.-M. Kuo, Che-Wei Lin, Wei Chen, M. L. Lee, L.-J. Yan, and J.-K. Sheu "Study of efficiency-droop mechanism in vertical red light-emitting diodes using electrical-to-optical impulse responses", Proc. SPIE 8278, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVI, 82781S (6 February 2012); https://doi.org/10.1117/12.906990

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