This article was presented as part of Symposium G, "Gallium Nitride and Related Alloys" at the 1998 Fall Meeting of the Materials Research Society held in Boston, Massachusetts, November 30-December 4.

Abstract

We have investigated the thermal stability of GaN using Raman scattering. Noninvasive optical monitoring of the degradation of GaN during high-temperature processing has been demonstrated. GaN samples grown by molecular-beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOCVD) were studied. Characteristic features in the Raman spectrum identify three thermal stability regimes: (1) annealing below 900°C does not affect the GaN Raman spectrum; (2) annealing between 900°C and 1000°C results in the appearance of disorder-induced Raman scattering between the E₂ and A₁(LO) phonon; (3) annealing at temperatures higher than 1000°C gives rise to distinct Raman modes at 630 cm^-1 , 656 cm^-1 and 770 cm^-1 . The evolution of the Raman spectrum of GaN with increasing annealing temperature is discussed in terms of disorder-induced Raman scattering. We find clear indications for an interfacial reaction between GaN and sapphire for annealing temperatures higher than 1000°C.

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Cite this article as: MRS Internet J. Nitride Semicond. Res. 4S1, G6.28 (1999).

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