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 |
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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 |
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