Characteristics of GaN-based light emitting diodes with different thicknesses of buffer layer grown by HVPE and MOCVD

Pengfei Tian, Paul R. Edwards, Michael J. Wallace, Robert W. Martin, Jonathan J.D. McKendry, Erdan Gu, Martin D. Dawson, Zhi-Jun Qiu, Chuanyu Jia, Zhizhong Chen, Guoyi Zhang, Lirong Zheng, Ran Liu

Research output: Contribution to journalArticle

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Abstract

GaN-based light emitting diodes (LEDs) have been fabricated on sapphire
substrates with different thicknesses of GaN buffer layer grown by a combination of hydride vapor phase epitaxy and metalorganic chemical vapor deposition. We analyzed the LED efficiency and modulation characteristics with buffer thicknesses of 12 µm and 30 µm. With the buffer thickness increase, cathodoluminescence hyperspectral imaging shows that the dislocation density in the buffer layer decreases from ∼1.3X10 8 cm-2 to∼1.0 X 10 8 cm-2, and Raman spectra suggest that the compressive stress in the quantum wells is partly relaxed, which leads to a large blue shift in the peak emission
wavelength of the photoluminescence and electroluminescent spectra. The combined effects of the low dislocation density and stress relaxation lead to improvements in the efficiency of LEDs with the 30 µm GaN buffer, but the electrical-to-optical modulation bandwidth is higher for the LEDs with the 12 µm GaN buffer. A rate equation analysis suggests that defect-related nonradiative recombination can help increase the modulation bandwidth but reduce the LED efficiency at low currents, suggesting that a compromise should be made in the choice of defect density.
LanguageEnglish
Article number075101
Number of pages12
JournalJournal of Physics D: Applied Physics
Volume50
Issue number7
DOIs
Publication statusPublished - 23 Jan 2017

Fingerprint

Metallorganic chemical vapor deposition
Buffer layers
metalorganic chemical vapor deposition
Light emitting diodes
light emitting diodes
buffers
Buffers
Modulation
Bandwidth
Vapor phase epitaxy
Cathodoluminescence
Light modulation
Defect density
bandwidth
modulation
Stress relaxation
Compressive stress
Hydrides
light modulation
Semiconductor quantum wells

Keywords

  • light emitting diode
  • GaN
  • buffer
  • modulation bandwidth
  • solid state lighting

Cite this

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title = "Characteristics of GaN-based light emitting diodes with different thicknesses of buffer layer grown by HVPE and MOCVD",
abstract = "GaN-based light emitting diodes (LEDs) have been fabricated on sapphiresubstrates with different thicknesses of GaN buffer layer grown by a combination of hydride vapor phase epitaxy and metalorganic chemical vapor deposition. We analyzed the LED efficiency and modulation characteristics with buffer thicknesses of 12 µm and 30 µm. With the buffer thickness increase, cathodoluminescence hyperspectral imaging shows that the dislocation density in the buffer layer decreases from ∼1.3X10 8 cm-2 to∼1.0 X 10 8 cm-2, and Raman spectra suggest that the compressive stress in the quantum wells is partly relaxed, which leads to a large blue shift in the peak emissionwavelength of the photoluminescence and electroluminescent spectra. The combined effects of the low dislocation density and stress relaxation lead to improvements in the efficiency of LEDs with the 30 µm GaN buffer, but the electrical-to-optical modulation bandwidth is higher for the LEDs with the 12 µm GaN buffer. A rate equation analysis suggests that defect-related nonradiative recombination can help increase the modulation bandwidth but reduce the LED efficiency at low currents, suggesting that a compromise should be made in the choice of defect density.",
keywords = "light emitting diode, GaN, buffer, modulation bandwidth, solid state lighting",
author = "Pengfei Tian and Edwards, {Paul R.} and Wallace, {Michael J.} and Martin, {Robert W.} and McKendry, {Jonathan J.D.} and Erdan Gu and Dawson, {Martin D.} and Zhi-Jun Qiu and Chuanyu Jia and Zhizhong Chen and Guoyi Zhang and Lirong Zheng and Ran Liu",
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Characteristics of GaN-based light emitting diodes with different thicknesses of buffer layer grown by HVPE and MOCVD. / Tian, Pengfei; Edwards, Paul R.; Wallace, Michael J.; Martin, Robert W.; McKendry, Jonathan J.D.; Gu, Erdan; Dawson, Martin D.; Qiu, Zhi-Jun; Jia, Chuanyu ; Chen, Zhizhong; Zhang, Guoyi; Zheng, Lirong ; Liu, Ran.

In: Journal of Physics D: Applied Physics, Vol. 50, No. 7, 075101, 23.01.2017.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Characteristics of GaN-based light emitting diodes with different thicknesses of buffer layer grown by HVPE and MOCVD

AU - Tian, Pengfei

AU - Edwards, Paul R.

AU - Wallace, Michael J.

AU - Martin, Robert W.

AU - McKendry, Jonathan J.D.

AU - Gu, Erdan

AU - Dawson, Martin D.

AU - Qiu, Zhi-Jun

AU - Jia, Chuanyu

AU - Chen, Zhizhong

AU - Zhang, Guoyi

AU - Zheng, Lirong

AU - Liu, Ran

PY - 2017/1/23

Y1 - 2017/1/23

N2 - GaN-based light emitting diodes (LEDs) have been fabricated on sapphiresubstrates with different thicknesses of GaN buffer layer grown by a combination of hydride vapor phase epitaxy and metalorganic chemical vapor deposition. We analyzed the LED efficiency and modulation characteristics with buffer thicknesses of 12 µm and 30 µm. With the buffer thickness increase, cathodoluminescence hyperspectral imaging shows that the dislocation density in the buffer layer decreases from ∼1.3X10 8 cm-2 to∼1.0 X 10 8 cm-2, and Raman spectra suggest that the compressive stress in the quantum wells is partly relaxed, which leads to a large blue shift in the peak emissionwavelength of the photoluminescence and electroluminescent spectra. The combined effects of the low dislocation density and stress relaxation lead to improvements in the efficiency of LEDs with the 30 µm GaN buffer, but the electrical-to-optical modulation bandwidth is higher for the LEDs with the 12 µm GaN buffer. A rate equation analysis suggests that defect-related nonradiative recombination can help increase the modulation bandwidth but reduce the LED efficiency at low currents, suggesting that a compromise should be made in the choice of defect density.

AB - GaN-based light emitting diodes (LEDs) have been fabricated on sapphiresubstrates with different thicknesses of GaN buffer layer grown by a combination of hydride vapor phase epitaxy and metalorganic chemical vapor deposition. We analyzed the LED efficiency and modulation characteristics with buffer thicknesses of 12 µm and 30 µm. With the buffer thickness increase, cathodoluminescence hyperspectral imaging shows that the dislocation density in the buffer layer decreases from ∼1.3X10 8 cm-2 to∼1.0 X 10 8 cm-2, and Raman spectra suggest that the compressive stress in the quantum wells is partly relaxed, which leads to a large blue shift in the peak emissionwavelength of the photoluminescence and electroluminescent spectra. The combined effects of the low dislocation density and stress relaxation lead to improvements in the efficiency of LEDs with the 30 µm GaN buffer, but the electrical-to-optical modulation bandwidth is higher for the LEDs with the 12 µm GaN buffer. A rate equation analysis suggests that defect-related nonradiative recombination can help increase the modulation bandwidth but reduce the LED efficiency at low currents, suggesting that a compromise should be made in the choice of defect density.

KW - light emitting diode

KW - GaN

KW - buffer

KW - modulation bandwidth

KW - solid state lighting

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