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

Prerna Chauhan, S Hasenöhrl , E Dobročka, M P Chauvat, A Minj, Filip Gucmann, Ľ Vančo, J Kováč, Jr., S Kret, P Ruterana, Martin Kuball, P Šiffalovič, J Kuzmík

Research output: Contribution to journalArticle (Academic Journal)peer-review

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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.

Original languageEnglish
Article number105304
Number of pages11
JournalJournal of Applied Physics
Volume125
Issue number10
Early online date14 Mar 2019
DOIs
Publication statusPublished - 14 Mar 2019

Structured keywords

  • CDTR

Keywords

  • 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

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