Evolution of threading dislocations in MOCVD-grown GaN films on (1 1 1) Si substrates

X. Weng, S. Raghavan, J. D. Acord, A. Jain, E. C. Dickey, J. M. Redwing

Research output: Contribution to journalArticle

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Abstract

We have quantitatively compared the evolution of threading dislocations (TDs) in GaN films grown on (1 1 1) Si substrates using different buffer/interlayer structures: a compositionally graded AlxGa1-xN (0≤x≤1) buffer layer, a thin high-temperature (HT) AlN interlayer (IL), and an AlN/GaN/AlxGa1-xN multilayer. Plan-view transmission electron microscopy (TEM) shows a reduction in TD density in GaN films grown on graded AlxGa1-xN buffer layers, and an increase in TD density in GaN films grown on HT AlN ILs, in comparison with those grown directly on an AlN buffer layer. Cross-sectional TEM reveals bending and annihilation of TDs within the graded AlxGa1-xN buffer layer, which lead to a decrease of TD density in the overgrown GaN films. On the other hand, a high density of TDs forms at the GaN/AlN IL interface, resulting in an increase in TD density in the GaN film. In addition, growing a thin AlN+GaN bilayer before growing the compositionally graded AlxGa1-xN buffer layer significantly reduces the TD density in the AlxGa1-xN buffer layer, which subsequently further reduces the TD density in the overgrown GaN film.

Original languageEnglish (US)
Pages (from-to)217-222
Number of pages6
JournalJournal of Crystal Growth
Volume300
Issue number1
DOIs
Publication statusPublished - Mar 1 2007

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

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