Cross-sectional and plan-view cathodoluminescence of GaN partially coalesced above a nanocolumn array

K. J. Lethy, P. R. Edwards, C. Liu, W. N. Wang, R. W. Martin

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Abstract

The optical properties of GaN layers coalesced above an array of nanocolumns have important consequences for advanced optoelectronic devices. GaN nanocolumns coalesced using a nanoscale epitaxial overgrowth technique have been investigated by high resolution cathodoluminescence (CL) hyperspectral imaging. Plan-view microscopy reveals partially coalesced GaN layers with a sub-μm scale domain structure and distinct grain boundaries, which is mapped using CL spectroscopy showing high strain at the grain boundaries. Cross-sectional areas spanning the partially coalesced GaN and underlying nanocolumns are mapped using CL, revealing that the GaN bandedge peak shifts by about 25 meV across the partially coalesced layer of ∼2 μm thick. The GaN above the nanocolumns remains under tensile strain, probably due to Si out-diffusion from the mask or substrate. The cross-sectional data show how this strain is reduced towards the surface of the partially coalesced layer, possibly due to misalignment between adjacent partially coalesced regions.
Original languageEnglish
Article number023507
Number of pages7
JournalJournal of Applied Physics
Volume112
Issue number2
Early online date19 Jul 2012
DOIs
Publication statusPublished - Jul 2012

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cathodoluminescence
grain boundaries
optoelectronic devices
misalignment
masks
microscopy
optical properties
shift
high resolution
spectroscopy

Keywords

  • cathodoluminescence
  • nanostructured materials
  • tensile strength
  • semiconductor growth
  • gallium compounds

Cite this

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abstract = "The optical properties of GaN layers coalesced above an array of nanocolumns have important consequences for advanced optoelectronic devices. GaN nanocolumns coalesced using a nanoscale epitaxial overgrowth technique have been investigated by high resolution cathodoluminescence (CL) hyperspectral imaging. Plan-view microscopy reveals partially coalesced GaN layers with a sub-μm scale domain structure and distinct grain boundaries, which is mapped using CL spectroscopy showing high strain at the grain boundaries. Cross-sectional areas spanning the partially coalesced GaN and underlying nanocolumns are mapped using CL, revealing that the GaN bandedge peak shifts by about 25 meV across the partially coalesced layer of ∼2 μm thick. The GaN above the nanocolumns remains under tensile strain, probably due to Si out-diffusion from the mask or substrate. The cross-sectional data show how this strain is reduced towards the surface of the partially coalesced layer, possibly due to misalignment between adjacent partially coalesced regions.",
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Cross-sectional and plan-view cathodoluminescence of GaN partially coalesced above a nanocolumn array. / Lethy, K. J.; Edwards, P. R.; Liu, C.; Wang, W. N.; Martin, R. W.

In: Journal of Applied Physics, Vol. 112, No. 2, 023507, 07.2012.

Research output: Contribution to journalArticle

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AU - Lethy, K. J.

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AU - Liu, C.

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AU - Martin, R. W.

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