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

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

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.

Original languageEnglish
Title of host publicationLight-Emitting Diodes
Subtitle of host publicationMaterials, Devices, and Applications for Solid State Lighting XVI
DOIs
StatePublished - 2012
EventLight-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVI - San Francisco, CA, United States
Duration: 24 Jan 201226 Jan 2012

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume8278
ISSN (Print)0277-786X

Conference

ConferenceLight-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVI
Country/TerritoryUnited States
CitySan Francisco, CA
Period24/01/1226/01/12

Keywords

  • AlGaInP
  • E-O impulse responses
  • efficiency-droop
  • Light-emitting diodes

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