Generated carrier dynamics in V-pit enhanced InGaN/GaN light emitting diode

Idris. A. Ajia, Paul R. Edwards, Yusin Pak, Ermek Belekov, Manuel A. Roldan, Nini Wei, Zhiqiang Liu, Robert W. Martin, Iman S. Roqan

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We investigate the effects of V-pits on the optical properties of a state-of-the art highly efficient, blue InGaN/GaN multi-quantum-well (MQW) light emitting diode (LED) with high internal quantum efficiency (IQE) of > 80%. The LED is structurally enhanced by incorporating pre-MQW InGaN strain relief layer with low InN content and patterned sapphire substrate. For comparison, a conventional (unenhanced) InGaN/GaN MQW LED (with IQE of 46%) grown under similar conditions was subjected to the same measurements. Scanning transmission electron microscopy (STEM) reveals the absence of V-pits in the unenhanced LED, whereas in the enhanced LED, V-pits with {10-11} facets, emerging from threading dislocations (TDs) were prominent. Cathodoluminescence mapping reveals the luminescence properties near the V-pits, showing that the formation of V-pit defects can encourage the growth of defect-neutralizing barriers around TD defect states. The diminished contribution of TDs in the MQWs allows indium-rich localization sites to act as efficient recombination centers. Photoluminescence and time-resolved spectroscopy measurements suggest that the V-pits play a significant role in the generated carrier rate and droop mechanism, showing that the quantum confined Stark effect is suppressed at low generated carrier density, after which the carrier dynamics and droop are governed by the carrier overflow effect.
LanguageEnglish
Pages820-826
Number of pages7
JournalACS Photonics
Volume5
Issue number3
DOIs
Publication statusPublished - 21 Mar 2018

Fingerprint

Light emitting diodes
light emitting diodes
Light
Semiconductor quantum wells
Quantum efficiency
Defects
quantum wells
quantum efficiency
defects
Stark effect
Scanning Transmission Electron Microscopy
Indium
Cathodoluminescence
Aluminum Oxide
Luminescence
Sapphire
Genetic Recombination
Carrier concentration
cathodoluminescence
Spectrum Analysis

Keywords

  • InGaN
  • efficiency droop
  • light emitting diode
  • carrier dynamics
  • time-resolved spectroscopy

Cite this

Ajia, I. A., Edwards, P. R., Pak, Y., Belekov, E., Roldan, M. A., Wei, N., ... Roqan, I. S. (2018). Generated carrier dynamics in V-pit enhanced InGaN/GaN light emitting diode. ACS Photonics, 5(3), 820-826. https://doi.org/10.1021/acsphotonics.7b00944
Ajia, Idris. A. ; Edwards, Paul R. ; Pak, Yusin ; Belekov, Ermek ; Roldan, Manuel A. ; Wei, Nini ; Liu, Zhiqiang ; Martin, Robert W. ; Roqan, Iman S. / Generated carrier dynamics in V-pit enhanced InGaN/GaN light emitting diode. In: ACS Photonics. 2018 ; Vol. 5, No. 3. pp. 820-826.
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abstract = "We investigate the effects of V-pits on the optical properties of a state-of-the art highly efficient, blue InGaN/GaN multi-quantum-well (MQW) light emitting diode (LED) with high internal quantum efficiency (IQE) of > 80{\%}. The LED is structurally enhanced by incorporating pre-MQW InGaN strain relief layer with low InN content and patterned sapphire substrate. For comparison, a conventional (unenhanced) InGaN/GaN MQW LED (with IQE of 46{\%}) grown under similar conditions was subjected to the same measurements. Scanning transmission electron microscopy (STEM) reveals the absence of V-pits in the unenhanced LED, whereas in the enhanced LED, V-pits with {10-11} facets, emerging from threading dislocations (TDs) were prominent. Cathodoluminescence mapping reveals the luminescence properties near the V-pits, showing that the formation of V-pit defects can encourage the growth of defect-neutralizing barriers around TD defect states. The diminished contribution of TDs in the MQWs allows indium-rich localization sites to act as efficient recombination centers. Photoluminescence and time-resolved spectroscopy measurements suggest that the V-pits play a significant role in the generated carrier rate and droop mechanism, showing that the quantum confined Stark effect is suppressed at low generated carrier density, after which the carrier dynamics and droop are governed by the carrier overflow effect.",
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Ajia, IA, Edwards, PR, Pak, Y, Belekov, E, Roldan, MA, Wei, N, Liu, Z, Martin, RW & Roqan, IS 2018, 'Generated carrier dynamics in V-pit enhanced InGaN/GaN light emitting diode' ACS Photonics, vol. 5, no. 3, pp. 820-826. https://doi.org/10.1021/acsphotonics.7b00944

Generated carrier dynamics in V-pit enhanced InGaN/GaN light emitting diode. / Ajia, Idris. A.; Edwards, Paul R.; Pak, Yusin; Belekov, Ermek; Roldan, Manuel A.; Wei, Nini; Liu, Zhiqiang; Martin, Robert W.; Roqan, Iman S.

In: ACS Photonics, Vol. 5, No. 3, 21.03.2018, p. 820-826.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Generated carrier dynamics in V-pit enhanced InGaN/GaN light emitting diode

AU - Ajia, Idris. A.

AU - Edwards, Paul R.

AU - Pak, Yusin

AU - Belekov, Ermek

AU - Roldan, Manuel A.

AU - Wei, Nini

AU - Liu, Zhiqiang

AU - Martin, Robert W.

AU - Roqan, Iman S.

PY - 2018/3/21

Y1 - 2018/3/21

N2 - We investigate the effects of V-pits on the optical properties of a state-of-the art highly efficient, blue InGaN/GaN multi-quantum-well (MQW) light emitting diode (LED) with high internal quantum efficiency (IQE) of > 80%. The LED is structurally enhanced by incorporating pre-MQW InGaN strain relief layer with low InN content and patterned sapphire substrate. For comparison, a conventional (unenhanced) InGaN/GaN MQW LED (with IQE of 46%) grown under similar conditions was subjected to the same measurements. Scanning transmission electron microscopy (STEM) reveals the absence of V-pits in the unenhanced LED, whereas in the enhanced LED, V-pits with {10-11} facets, emerging from threading dislocations (TDs) were prominent. Cathodoluminescence mapping reveals the luminescence properties near the V-pits, showing that the formation of V-pit defects can encourage the growth of defect-neutralizing barriers around TD defect states. The diminished contribution of TDs in the MQWs allows indium-rich localization sites to act as efficient recombination centers. Photoluminescence and time-resolved spectroscopy measurements suggest that the V-pits play a significant role in the generated carrier rate and droop mechanism, showing that the quantum confined Stark effect is suppressed at low generated carrier density, after which the carrier dynamics and droop are governed by the carrier overflow effect.

AB - We investigate the effects of V-pits on the optical properties of a state-of-the art highly efficient, blue InGaN/GaN multi-quantum-well (MQW) light emitting diode (LED) with high internal quantum efficiency (IQE) of > 80%. The LED is structurally enhanced by incorporating pre-MQW InGaN strain relief layer with low InN content and patterned sapphire substrate. For comparison, a conventional (unenhanced) InGaN/GaN MQW LED (with IQE of 46%) grown under similar conditions was subjected to the same measurements. Scanning transmission electron microscopy (STEM) reveals the absence of V-pits in the unenhanced LED, whereas in the enhanced LED, V-pits with {10-11} facets, emerging from threading dislocations (TDs) were prominent. Cathodoluminescence mapping reveals the luminescence properties near the V-pits, showing that the formation of V-pit defects can encourage the growth of defect-neutralizing barriers around TD defect states. The diminished contribution of TDs in the MQWs allows indium-rich localization sites to act as efficient recombination centers. Photoluminescence and time-resolved spectroscopy measurements suggest that the V-pits play a significant role in the generated carrier rate and droop mechanism, showing that the quantum confined Stark effect is suppressed at low generated carrier density, after which the carrier dynamics and droop are governed by the carrier overflow effect.

KW - InGaN

KW - efficiency droop

KW - light emitting diode

KW - carrier dynamics

KW - time-resolved spectroscopy

UR - http://pubs.acs.org/journal/apchd5

U2 - 10.1021/acsphotonics.7b00944

DO - 10.1021/acsphotonics.7b00944

M3 - Article

VL - 5

SP - 820

EP - 826

JO - ACS Photonics

T2 - ACS Photonics

JF - ACS Photonics

SN - 2330-4022

IS - 3

ER -