Evolution of the m-plane quantum well morphology and composition within a GaN/InGaN core–shell structure

Pierre-Marie Coulon, Shahrzad hosseini Vajargah, An Bao, Paul R. Edwards, Emmanuel D. Le Boulbar, Ionut Girgel, Robert W. Martin, Colin J. Humphreys, Rachel A. Oliver, Duncan W. E. Allsopp, Philip A. Shields

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

GaN/InGaN core-shell nanorods are promising for optoelectronic applications due to the absence of polarization-related electric fields on the sidewalls, a lower defect density, a larger emission volume and strain relaxation at the free surfaces. The core-shell geometry allows the growth of thicker InGaN shell layers, which would benefit the efficiency of light emitting diodes. However, the growth mode of such layers by metal organic vapor phase epitaxy is poorly understood. Through a combination of nanofabrication, epitaxial growth and detailed characterization, this work reveals an evolution in the growth mode of InGaN epitaxial shells, from a two dimensional (2D) growth mode to three dimensional (3D) striated growth without additional line defect formation with increasing layer thickness. Measurements of the indium distribution show fluctuations along the <10-10> directions, with low and high indium composition associated with the 2D and 3D growth modes, respectively. Atomic steps at the GaN/InGaN core-shell interface were observed to occur with a similar frequency as quasi-periodic indium fluctuations along [0001] observed within the 2D layer, to provide evidence that the resulting local strain relief at the steps acts as the trigger for a change of growth mode by elastic relaxation. This study demonstrates that misfit dislocation generation during the growth of wider InGaN shell layers can be avoided by using pre-etched GaN nanorods. Significantly, this enables the growth of absorption-based devices and light-emitting diodes with emissive layers wide enough to mitigate efficiency droop.
LanguageEnglish
Pages474-482
Number of pages9
JournalCrystal Growth and Design
Volume17
Issue number2
Early online date3 Jan 2017
DOIs
Publication statusPublished - 1 Feb 2017

Fingerprint

Shells (structures)
Semiconductor quantum wells
quantum wells
Chemical analysis
Indium
indium
Nanorods
Light emitting diodes
nanorods
light emitting diodes
Strain relaxation
Vapor phase epitaxy
Defect density
nanofabrication
Dislocations (crystals)
defects
Nanotechnology
Epitaxial growth
Optoelectronic devices
vapor phase epitaxy

Keywords

  • nanorod
  • core-shell
  • InGaN
  • m-plane
  • morphology
  • AFM
  • TEM
  • EDX
  • nanofabrication
  • epitaxial growth

Cite this

Coulon, Pierre-Marie ; Vajargah, Shahrzad hosseini ; Bao, An ; Edwards, Paul R. ; Le Boulbar, Emmanuel D. ; Girgel, Ionut ; Martin, Robert W. ; Humphreys, Colin J. ; Oliver, Rachel A. ; Allsopp, Duncan W. E. ; Shields, Philip A. / Evolution of the m-plane quantum well morphology and composition within a GaN/InGaN core–shell structure. In: Crystal Growth and Design. 2017 ; Vol. 17, No. 2. pp. 474-482.
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abstract = "GaN/InGaN core-shell nanorods are promising for optoelectronic applications due to the absence of polarization-related electric fields on the sidewalls, a lower defect density, a larger emission volume and strain relaxation at the free surfaces. The core-shell geometry allows the growth of thicker InGaN shell layers, which would benefit the efficiency of light emitting diodes. However, the growth mode of such layers by metal organic vapor phase epitaxy is poorly understood. Through a combination of nanofabrication, epitaxial growth and detailed characterization, this work reveals an evolution in the growth mode of InGaN epitaxial shells, from a two dimensional (2D) growth mode to three dimensional (3D) striated growth without additional line defect formation with increasing layer thickness. Measurements of the indium distribution show fluctuations along the <10-10> directions, with low and high indium composition associated with the 2D and 3D growth modes, respectively. Atomic steps at the GaN/InGaN core-shell interface were observed to occur with a similar frequency as quasi-periodic indium fluctuations along [0001] observed within the 2D layer, to provide evidence that the resulting local strain relief at the steps acts as the trigger for a change of growth mode by elastic relaxation. This study demonstrates that misfit dislocation generation during the growth of wider InGaN shell layers can be avoided by using pre-etched GaN nanorods. Significantly, this enables the growth of absorption-based devices and light-emitting diodes with emissive layers wide enough to mitigate efficiency droop.",
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author = "Pierre-Marie Coulon and Vajargah, {Shahrzad hosseini} and An Bao and Edwards, {Paul R.} and {Le Boulbar}, {Emmanuel D.} and Ionut Girgel and Martin, {Robert W.} and Humphreys, {Colin J.} and Oliver, {Rachel A.} and Allsopp, {Duncan W. E.} and Shields, {Philip A.}",
year = "2017",
month = "2",
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doi = "10.1021/acs.cgd.6b01281",
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Coulon, P-M, Vajargah, SH, Bao, A, Edwards, PR, Le Boulbar, ED, Girgel, I, Martin, RW, Humphreys, CJ, Oliver, RA, Allsopp, DWE & Shields, PA 2017, 'Evolution of the m-plane quantum well morphology and composition within a GaN/InGaN core–shell structure' Crystal Growth and Design, vol. 17, no. 2, pp. 474-482. https://doi.org/10.1021/acs.cgd.6b01281

Evolution of the m-plane quantum well morphology and composition within a GaN/InGaN core–shell structure. / Coulon, Pierre-Marie; Vajargah, Shahrzad hosseini; Bao, An; Edwards, Paul R.; Le Boulbar, Emmanuel D.; Girgel, Ionut; Martin, Robert W.; Humphreys, Colin J.; Oliver, Rachel A.; Allsopp, Duncan W. E.; Shields, Philip A.

In: Crystal Growth and Design, Vol. 17, No. 2, 01.02.2017, p. 474-482.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Evolution of the m-plane quantum well morphology and composition within a GaN/InGaN core–shell structure

AU - Coulon, Pierre-Marie

AU - Vajargah, Shahrzad hosseini

AU - Bao, An

AU - Edwards, Paul R.

AU - Le Boulbar, Emmanuel D.

AU - Girgel, Ionut

AU - Martin, Robert W.

AU - Humphreys, Colin J.

AU - Oliver, Rachel A.

AU - Allsopp, Duncan W. E.

AU - Shields, Philip A.

PY - 2017/2/1

Y1 - 2017/2/1

N2 - GaN/InGaN core-shell nanorods are promising for optoelectronic applications due to the absence of polarization-related electric fields on the sidewalls, a lower defect density, a larger emission volume and strain relaxation at the free surfaces. The core-shell geometry allows the growth of thicker InGaN shell layers, which would benefit the efficiency of light emitting diodes. However, the growth mode of such layers by metal organic vapor phase epitaxy is poorly understood. Through a combination of nanofabrication, epitaxial growth and detailed characterization, this work reveals an evolution in the growth mode of InGaN epitaxial shells, from a two dimensional (2D) growth mode to three dimensional (3D) striated growth without additional line defect formation with increasing layer thickness. Measurements of the indium distribution show fluctuations along the <10-10> directions, with low and high indium composition associated with the 2D and 3D growth modes, respectively. Atomic steps at the GaN/InGaN core-shell interface were observed to occur with a similar frequency as quasi-periodic indium fluctuations along [0001] observed within the 2D layer, to provide evidence that the resulting local strain relief at the steps acts as the trigger for a change of growth mode by elastic relaxation. This study demonstrates that misfit dislocation generation during the growth of wider InGaN shell layers can be avoided by using pre-etched GaN nanorods. Significantly, this enables the growth of absorption-based devices and light-emitting diodes with emissive layers wide enough to mitigate efficiency droop.

AB - GaN/InGaN core-shell nanorods are promising for optoelectronic applications due to the absence of polarization-related electric fields on the sidewalls, a lower defect density, a larger emission volume and strain relaxation at the free surfaces. The core-shell geometry allows the growth of thicker InGaN shell layers, which would benefit the efficiency of light emitting diodes. However, the growth mode of such layers by metal organic vapor phase epitaxy is poorly understood. Through a combination of nanofabrication, epitaxial growth and detailed characterization, this work reveals an evolution in the growth mode of InGaN epitaxial shells, from a two dimensional (2D) growth mode to three dimensional (3D) striated growth without additional line defect formation with increasing layer thickness. Measurements of the indium distribution show fluctuations along the <10-10> directions, with low and high indium composition associated with the 2D and 3D growth modes, respectively. Atomic steps at the GaN/InGaN core-shell interface were observed to occur with a similar frequency as quasi-periodic indium fluctuations along [0001] observed within the 2D layer, to provide evidence that the resulting local strain relief at the steps acts as the trigger for a change of growth mode by elastic relaxation. This study demonstrates that misfit dislocation generation during the growth of wider InGaN shell layers can be avoided by using pre-etched GaN nanorods. Significantly, this enables the growth of absorption-based devices and light-emitting diodes with emissive layers wide enough to mitigate efficiency droop.

KW - nanorod

KW - core-shell

KW - InGaN

KW - m-plane

KW - morphology

KW - AFM

KW - TEM

KW - EDX

KW - nanofabrication

KW - epitaxial growth

UR - http://pubs.acs.org/doi/abs/10.1021/acs.cgd.6b01281

U2 - 10.1021/acs.cgd.6b01281

DO - 10.1021/acs.cgd.6b01281

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EP - 482

JO - Crystal Growth and Design

T2 - Crystal Growth and Design

JF - Crystal Growth and Design

SN - 1528-7483

IS - 2

ER -