The diffusion of Mg was studied in GaN layers grown onto sapphire substrates by atmospheric-pressure metalorganic vapor-phase-epitaxy in a so-called home-made reactor. Secondary ion mass spectroscopy was used to visualise the Mg profiles in 2 types of multi sub-layer GaN structures. One structure was grown with a variable flow of Ga precursor, and the other with a variable growth temperature. In both cases, the Mg dopant precursor (Cp2Mg) flow was constant. Using Fick's second law to fit the experimental secondary ion mass spectroscopy data, an increasing and then saturating Mg diffusion coefficient versus Mg concentration was found. The Mg incorporation was found to become greater when the Ga precursor flow was reduced. Based upon the temperature-related behaviour, it was found that the Mg diffusivity was described by:D (cm2/s) = 2.8 x 10-7 exp[-1.9(eV)/kT]

It was suggested that Mg diffused via substitutional sites.

Magnesium Diffusion Profile in GaN Grown by MOVPE. Z.Benzarti, I.Halidou, Z.Bougrioua, T.Boufaden, B.El Jania: Journal of Crystal Growth, 2008, 310[14], 3274-7