The adsorption, diffusion and dissociation of precursor species, monomethylgallium and NH3, on the GaN (00•1) surface were investigated using density functional theory calculations, combined with a GaN (00•1) surface cluster model. The dissociation of NH3 on the surface was easy, with a low activation barrier. A combined analysis with the surface diffusion of adatoms demonstrated that Ga(ad) and NH(ad) became primary reactant species for 2D film growth, and that N(ad) developed into a nucleation center. The studies suggested that control of NH3(ad) dissociation was essential to improving epitaxial film quality.

Computational Study of Adsorption, Diffusion, and Dissociation of Precursor Species on the GaN (0001) Surface during GaN MOCVD. Y.S.Won, J.Lee, C.S.Kim, S.S.Park: Surface Science, 2009, 603[4], L31-4