Mechanism of enhanced light output in InGaN-based microlight emitting diodes

H.W. Choi, C.W. Jeon, M.D. Dawson, P.R. Edwards, S. Tripathy, R.W. Martin

Research output: Contribution to journalArticle

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Abstract

Micro-light emitting diode (LED) arrays with diameters of 4 to 20 mum have been fabricated and were found to be much more efficient light emitters compared to their broad-area counterparts, with up to five times enhancement in optical power densities. The possible mechanisms responsible for the improvement in performance were investigated. Strain relaxation in the microstructures as measured by Raman spectroscopy was not observed, arguing against theories of an increase in internal quantum efficiency due to a reduction of the piezoelectric field put forward by other groups. Optical microscope images show intense light emission at the periphery of the devices, as a result of light scattering off the etched sidewalls. This increases the extraction efficiency relative to broad area devices and boosts the forward optical output. In addition, spectra of the forward emitted light reveal the presence of resonant cavity modes [whispering gallery (WG) modes in particular] which appear to play a role in enhancing the optical output.
LanguageEnglish
Pages5978-5982
Number of pages4
JournalJournal of Applied Physics
Volume93
Issue number10
DOIs
Publication statusPublished - May 2003

Fingerprint

diodes
whispering gallery modes
output
cavity resonators
acceleration (physics)
optical microscopes
light emission
radiant flux density
quantum efficiency
emitters
light scattering
light emitting diodes
Raman spectroscopy
microstructure
augmentation

Keywords

  • indium compounds
  • gallium compounds
  • light emitting diodes
  • quantum well devices
  • semiconductor quantum wells
  • III-V semiconductors
  • wide band gap semiconductors
  • Raman spectra
  • cathodoluminescence
  • electroluminescence
  • optical microscopy

Cite this

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title = "Mechanism of enhanced light output in InGaN-based microlight emitting diodes",
abstract = "Micro-light emitting diode (LED) arrays with diameters of 4 to 20 mum have been fabricated and were found to be much more efficient light emitters compared to their broad-area counterparts, with up to five times enhancement in optical power densities. The possible mechanisms responsible for the improvement in performance were investigated. Strain relaxation in the microstructures as measured by Raman spectroscopy was not observed, arguing against theories of an increase in internal quantum efficiency due to a reduction of the piezoelectric field put forward by other groups. Optical microscope images show intense light emission at the periphery of the devices, as a result of light scattering off the etched sidewalls. This increases the extraction efficiency relative to broad area devices and boosts the forward optical output. In addition, spectra of the forward emitted light reveal the presence of resonant cavity modes [whispering gallery (WG) modes in particular] which appear to play a role in enhancing the optical output.",
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Mechanism of enhanced light output in InGaN-based microlight emitting diodes. / Choi, H.W.; Jeon, C.W.; Dawson, M.D.; Edwards, P.R.; Tripathy, S.; Martin, R.W.

In: Journal of Applied Physics, Vol. 93, No. 10, 05.2003, p. 5978-5982.

Research output: Contribution to journalArticle

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T1 - Mechanism of enhanced light output in InGaN-based microlight emitting diodes

AU - Choi, H.W.

AU - Jeon, C.W.

AU - Dawson, M.D.

AU - Edwards, P.R.

AU - Tripathy, S.

AU - Martin, R.W.

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AB - Micro-light emitting diode (LED) arrays with diameters of 4 to 20 mum have been fabricated and were found to be much more efficient light emitters compared to their broad-area counterparts, with up to five times enhancement in optical power densities. The possible mechanisms responsible for the improvement in performance were investigated. Strain relaxation in the microstructures as measured by Raman spectroscopy was not observed, arguing against theories of an increase in internal quantum efficiency due to a reduction of the piezoelectric field put forward by other groups. Optical microscope images show intense light emission at the periphery of the devices, as a result of light scattering off the etched sidewalls. This increases the extraction efficiency relative to broad area devices and boosts the forward optical output. In addition, spectra of the forward emitted light reveal the presence of resonant cavity modes [whispering gallery (WG) modes in particular] which appear to play a role in enhancing the optical output.

KW - indium compounds

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KW - wide band gap semiconductors

KW - Raman spectra

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