This article was presented as part of Symposium W, "Gallium Nitride and Related Alloys" at the 1999 Fall Meeting of the Materials Research Society held in Boston, Massachusetts, November 28-December 3

Abstract

GaN decomposition was studied above 800 °C in flowing H₂ and N₂ for pressures ranging from 10 to 700 torr. From careful weighings of the GaN film on sapphire before and after annealing, the rates for GaN decomposition, Ga surface accumulation, and Ga desorption were obtained. An enhancement in the GaN decomposition rate was observed in H₂ pressures greater than 100 torr. Even with this enhanced GaN decomposition, the Ga desorption rate is nearly constant at higher pressures. As a result, Ga droplets accumulate on the surface. For N₂ pressures ranging from 76 to 400 torr no net enhancement in the GaN decomposition rate is observed and the GaN decomposition rate is reduced compared to identical annealing conditions in H₂. This suggests that H₂ is acting chemically to reduce the barrier for GaN decomposition. This may occur through a surface mediated dissociation of H₂ followed by the formation of more mobile and volatile hydrogenated N and Ga species. The significance of this study for GaN growth is that by increasing the GaN decomposition, the Ga atoms diffuse farther and subsequently re-incorporate into the growing lattice, increasing the GaN crystal quality. Connections between the enhanced GaN decomposition rate and the coalescing of nucleation layer during the ramp to high temperature and the consequences for the high temperature growth are discussed.

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References Citing this Article

[1] M. Callahan, M. Harris, M. Suscavage, D. Bliss, J. Bailey, MRS Internet J. Nitride Semicond. Res. 4, 10 (1999).

Cite this article as: MRS Internet J. Nitride Semicond. Res. 4S1, G3.70 (2000).

Errata

1. August 25, 1999. In the original version of this paper, the values of the GaN decomposition, Surface Ga, and Desorbed Ga rates shown in Fig. 2, 3, and 4 and in table I were calculated incorrectly. The calculated rates are 1000 times greater than they should be. All other data and conclusions in the letter remain valid and are unchanged. The authors apologize for the error and any misinterpretation of the data which may have occurred. Original Version (432K).

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