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Evidence of relationship between strain and In-incorporation: Growth of N-polar In-rich InAlN buffer layer by OMCVD

Research output: Contribution to journalArticle

Original languageEnglish
Article number105304
Number of pages11
JournalJournal of Applied Physics
Volume125
Issue number10
Early online date14 Mar 2019
DOIs
DateAccepted/In press - 2 Mar 2019
DateE-pub ahead of print - 14 Mar 2019
DatePublished (current) - 14 Mar 2019

Abstract

Two I n x A l 1 - x N layers were grown simultaneously on different substrates [sapphire (0001) and the Ga-polar GaN template], but under the same reactor conditions, they were employed to investigate the mechanism of strain-driven compositional evolution. The resulting layers on different substrates exhibit different polarities and the layer grown on sapphire is N-polar. Moreover, for the two substrates, the difference in the degree of relaxation of the grown layers was almost 100%, leading to a large In-molar fraction difference of 0.32. Incorporation of In in I n x A l 1 - x N layers was found to be significantly influenced by the strain imposed by the under-layers. With the evolutionary process of In-incorporation during subsequent layer growth along [0001], the direction of growth was investigated in detail by Auger electron spectroscopy. It is discovered that the I n 0.60 A l 0.40 N layer grown directly on sapphire consists of two different regions with different molar fractions: the transition region and the uniform region. According to the detailed cross-sectional transmission electron microscopy, the transition region is formed near the hetero-interface due to the partial strain release caused by the generation of misfit-dislocations. The magnitude of residual strain in the uniform region decides the In-molar fraction. I n x A l 1 - x N layers were analyzed by structural and optical characterization techniques. Our present work also shows that a multi-characterization approach to study I n x A l 1 - x N is a prerequisite for their applications as a buffer layer.

    Research areas

  • organometallic chemical vapor deposition, In-rich In_x Al_(1-x)N layer, high-resolution transmission electron microscopy, atomic scanning transmission electron microscopy, Auger electron spectroscopy

    Structured keywords

  • CDTR

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    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via AIP at https://aip.scitation.org/doi/abs/10.1063/1.5079756 . Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 1 MB, PDF-document

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