Distribution profiles of Ga and Al near to the interface of the n-GaN/sapphire system were determined by means of X-ray energy dispersive spectroscopy. It was found that Ga, diffusing into the sapphire substrate, obeyed the law-of-remainder probability function; giving a diffusivity of 2.30 x 10-13cm2/s. The diffusion was associated with GaN growth at high temperatures. When compared with the diffusion of Ga into the sapphire substrate, much less Al anti-diffusion from the substrate into the GaN film occurred; with a diffusivity of about 4.8 x 10-15cm2/s.

S.Fung, X.Xu, Y.Zhao, W.Sun, X.Chen, N.Sun, T.Sun, C.Jiang: Journal of Applied Physics, 1998, 84[4], 2355-7