Energy-dispersive x-ray imaging of an InGaN/GaN bilayer on sapphire

K. P. O'Donnell, P. G. Middleton, C. Trager-Cowan, C. Young, S. C. Bayliss, I. Fletcher, W. Van der Stricht, I. Moerman, P. Demeester

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Abstract

In this letter we discuss the potential and the limitations of quantitative characterization of the distribution of In and Ga atoms in III-N mixed alloys using energy dispersive x-ray (EDX) analysis. Spatial fluctuations of the indium content in an InGaN epilayer are found to correspond to changes in luminescence efficiency. Large hexagonal pyramids, which appear sparsely in such layers, appear to be relatively deficient in indium. Monte Carlo simulations, used to profile the GaKa x-ray fluorescence, highlight several limitations of the EDX technique in this context, but confirm our interpretation of the data. Finally, we identify differential growth rates as a possible explanation for the concentration/efficiency variations in InGaN layers.

Original languageEnglish
Pages (from-to)3273-3275
Number of pages3
JournalApplied Physics Letters
Volume73
Issue number22
DOIs
Publication statusPublished - 1 Nov 1998

Keywords

  • InGaN layers
  • x-ray fluorescence
  • sapphire

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