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Effect of temperature and mineralizer on phase stability and solubility of GaN under acidic ammonothermal conditions

Dirk Ehrentraut 1Yuji Kagamitani 1Naruhiro Hoshino 1Tsuguo Fukuda 1Hirohisa Itoh 2

1. Tohoku University, Sendai, Japan
2. Mitsubishii Chemical Corp., Ibaraki 300-1295, Japan

Abstract

The temperature effect of ammonium halogenides NH4X (X = Cl, Br, I) on the phase stability of GaN synthesized under supercritical ammonothermal conditions in the temperature range 400–550 °C has been investigated. Self-nucleated hexagonal GaN (h-GaN), cubic GaN (c-GaN), and gallium oxide (Ga2O3) has been crystallized. The latter was formed from mineralizers containing a relatively high amount of oxygen. The tendency to form c-GaN increases from X = Cl over Br to I. Decrasing the temperature supports the formation of c-GaN. Single-phase h-GaN can be grown from X = Cl, Br at 550 °C. Solubility of GaN is discussed. The use of h-GaN substrate has a phase-stabilizing effect and lowers the stability range for overgrown h-GaN films. We show how the choice of precursor will have an impact on a and c lattice parameter of self-nucleated h-GaN.

 

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Related papers

Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Dirk Ehrentraut
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth

Submitted: 2007-01-19 02:50
Revised:   2009-06-07 00:44