Abstract
We compare the structural and spectral properties of two multi quantum wells (MQWs), grown by metal organic chemical vapour deposition under the same nominal conditions, with a different number of periods. The MQWs, each with 20% InN and containing 8 and 18 wells, respectively, grew on-axis and coherent to GaN, as revealed by X-ray diffraction reciprocal space mapping (RSM) analysis. Comparison of the asymmetrical (105) RSMs indicates an overall structural deterioration and greater well-barrier intermixing for the MQW with the larger number of wells. Moreover, the composition of the MQWs was depth-profiled by grazing incidence Rutherford backscattering spectrometry (RBS). RBS further evidences strong intermixing in the 18-well heterostructure. The deleterious effects of intermixing on the emission spectrum are revealed by low temperature photoluminescence spectroscopy. Despite similar peak emission energies (ΔE < 45 meV) the 8-well structure shows a more symmetric and narrow peak (FWHM ≈ 100 meV) in comparison with that of the 18-well sample (FWHM ≈ 170 meV). Surface analyses by atomic force and scanning electron microscopy show an increased density, size and depth of V-pit defects on the 18-well structure. These results suggest that dislocations and pitting result from a larger elastic strain energy accumulated in the thicker MQW stack and are a fundamental intermixing mechanism for InGaN/GaN MQWs.
| Original language | English |
|---|---|
| Pages (from-to) | 302-306 |
| Number of pages | 5 |
| Journal | Physica Status Solidi C - Current Topics in Solid State Physics |
| Volume | 0 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Dec 2002 |
| Event | 2nd International Workshop on Nitride Semiconductors, IWN 2002 - Aachen, Germany Duration: 22 Jul 2002 → 25 Jul 2002 |
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Keywords
- multi quantum wells (MQWs)
- emission spectroscopy
- metallorganic chemical vapor deposition
- mixing
- nitrides
- optical properties
- photoluminescence spectroscopy
- rutherford backscattering spectroscopy
- scanning electron microscopy
- x ray diffraction
Cite this
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Degradation of structural and optical properties of InGaN/GaN multiple quantum wells with increasing number of wells. / Pereira, S.; Correia, M. R.; Pereira, E.; O'Donnell, K. P.; Alves, E.; Barradas, N. P.; Sequeira, A. D.; Franco, N.; Watson, I. M.; Liu, C.
In: Physica Status Solidi C - Current Topics in Solid State Physics, Vol. 0, No. 1, 01.12.2002, p. 302-306.Research output: Contribution to journal › Conference article
TY - JOUR
T1 - Degradation of structural and optical properties of InGaN/GaN multiple quantum wells with increasing number of wells
AU - Pereira, S.
AU - Correia, M. R.
AU - Pereira, E.
AU - O'Donnell, K. P.
AU - Alves, E.
AU - Barradas, N. P.
AU - Sequeira, A. D.
AU - Franco, N.
AU - Watson, I. M.
AU - Liu, C.
PY - 2002/12/1
Y1 - 2002/12/1
N2 - We compare the structural and spectral properties of two multi quantum wells (MQWs), grown by metal organic chemical vapour deposition under the same nominal conditions, with a different number of periods. The MQWs, each with 20% InN and containing 8 and 18 wells, respectively, grew on-axis and coherent to GaN, as revealed by X-ray diffraction reciprocal space mapping (RSM) analysis. Comparison of the asymmetrical (105) RSMs indicates an overall structural deterioration and greater well-barrier intermixing for the MQW with the larger number of wells. Moreover, the composition of the MQWs was depth-profiled by grazing incidence Rutherford backscattering spectrometry (RBS). RBS further evidences strong intermixing in the 18-well heterostructure. The deleterious effects of intermixing on the emission spectrum are revealed by low temperature photoluminescence spectroscopy. Despite similar peak emission energies (ΔE < 45 meV) the 8-well structure shows a more symmetric and narrow peak (FWHM ≈ 100 meV) in comparison with that of the 18-well sample (FWHM ≈ 170 meV). Surface analyses by atomic force and scanning electron microscopy show an increased density, size and depth of V-pit defects on the 18-well structure. These results suggest that dislocations and pitting result from a larger elastic strain energy accumulated in the thicker MQW stack and are a fundamental intermixing mechanism for InGaN/GaN MQWs.
AB - We compare the structural and spectral properties of two multi quantum wells (MQWs), grown by metal organic chemical vapour deposition under the same nominal conditions, with a different number of periods. The MQWs, each with 20% InN and containing 8 and 18 wells, respectively, grew on-axis and coherent to GaN, as revealed by X-ray diffraction reciprocal space mapping (RSM) analysis. Comparison of the asymmetrical (105) RSMs indicates an overall structural deterioration and greater well-barrier intermixing for the MQW with the larger number of wells. Moreover, the composition of the MQWs was depth-profiled by grazing incidence Rutherford backscattering spectrometry (RBS). RBS further evidences strong intermixing in the 18-well heterostructure. The deleterious effects of intermixing on the emission spectrum are revealed by low temperature photoluminescence spectroscopy. Despite similar peak emission energies (ΔE < 45 meV) the 8-well structure shows a more symmetric and narrow peak (FWHM ≈ 100 meV) in comparison with that of the 18-well sample (FWHM ≈ 170 meV). Surface analyses by atomic force and scanning electron microscopy show an increased density, size and depth of V-pit defects on the 18-well structure. These results suggest that dislocations and pitting result from a larger elastic strain energy accumulated in the thicker MQW stack and are a fundamental intermixing mechanism for InGaN/GaN MQWs.
KW - multi quantum wells (MQWs)
KW - emission spectroscopy
KW - metallorganic chemical vapor deposition
KW - mixing
KW - nitrides
KW - optical properties
KW - photoluminescence spectroscopy
KW - rutherford backscattering spectroscopy
KW - scanning electron microscopy
KW - x ray diffraction
UR - http://www.scopus.com/inward/record.url?scp=84875091108&partnerID=8YFLogxK
U2 - 10.1002/pssc.200390049
DO - 10.1002/pssc.200390049
M3 - Conference article
VL - 0
SP - 302
EP - 306
JO - Physica Status Solidi C - Current Topics in Solid State Physics
JF - Physica Status Solidi C - Current Topics in Solid State Physics
SN - 1610-1634
IS - 1
ER -