Temperature effect of ammonium halogenides as mineralizers on the phase stability of gallium nitride synthesized under acidic ammonothermal conditions

Dirk Ehrentraut, Naruhiro Hoshino, Yuji Kagamitani, Akira Yoshikawa, Tsuguo Fukuda, Hirohisa Itoh, Shinichiro Kawabata

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

The temperature effect of the ammonium halogenide mineralizers NH 4X (X = Cl, Br, I) on the phase stability of GaN synthesized under supercritical ammonothermal conditions in the temperature range 360-550 °C has been investigated. Hexagonal GaN (h-GaN) and cubic GaN (c-GaN) were crystallized. Oxygen impurities force the formation of gallium oxide at low temperatures. The tendency to form c-GaN increases from X = Cl to Br to I. Decreasing temperature supports this trend. Single-phase h-GaN can be grown from X = Cl at ≥470 °C, Br at ≥500 °C and I at ≥550 °C. Mixed mineralizers of type X = Cl + Br and Cl + I are useful to improve both the yield and the temperature stability range for h-GaN. The size of h-GaN crystals decreases from X = Cl to Br to I. The use of a h-GaN substrate has a phase-stabilizing effect and lowers the temperature stability range for overgrown h-GaN films. The choice of precursor will have an impact on the a and c lattice parameters of self-nucleated h-GaN.

Original languageEnglish
Pages (from-to)886-893
Number of pages8
JournalJournal of Materials Chemistry
Volume17
Issue number9
DOIs
Publication statusPublished - 2007 Feb 28

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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