Correlations between the morphology and emission properties of trench defects in InGaN/GaN quantum wells

F. C.-P. Massabuau*, L. Trinh-Xuan, D. Lodié, E. J. Thrush, D. Zhu, F. Oehler, T. Zhu, M. J. Kappers, C. J. Humphreys, R. A. Oliver

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)

Abstract

Atomic force microscopy (AFM) and scanning electron microscopy (SEM) with cathodoluminescence (CL) were performed on exactly the same defects in a blue-emitting InGaN/GaN multiple quantum well (QW) sample enabling the direct correlation of the morphology of an individual defect with its emission properties. The defects in question are observed in AFM and SEM as a trench partially or fully enclosing a region of the QW having altered emission properties. Their sub-surface structure has previously been shown to consist of a basal plane stacking fault (BSF) in the plane of the QW stack, and a stacking mismatch boundary (SMB) which opens up into a trench at the sample surface. In CL, the material enclosed by the trench may emit more or less intensely than the surrounding material, but always exhibits a redshift relative to the surrounding material. A strong correlation exists between the width of the trench and both the redshift and the intensity ratio, with the widest trenches surrounding regions which exhibit the brightest and most redshifted emission. Based on studies of the evolution of the trench width with the number of QWs from four additional MQW samples, we conclude that in order for a trench defect to emit intense, strongly redshifted light, the BSF must be formed in the early stages of the growth of the QW stack. The data suggest that the SMB may act as a non-radiative recombination center.

Original languageEnglish
Article number073505
Number of pages7
JournalJournal of Applied Physics
Volume113
Issue number7
Early online date15 Feb 2013
DOIs
Publication statusPublished - 21 Feb 2013

Funding

The European Research Council has provided financial support under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no 279361 (MACONS). FM and MJK acknowledge support from the EPSRC under EP/H0495331, as does TZ under EP/J003603/1.

Keywords

  • cathodoluminescence
  • scanning electron microscopy
  • atomic force microscopy
  • quantum well

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