Computational Study Of Adsorption, Diffusion, And Dissociation Of Precursor Species On The Gan (0001) Surface During Gan Mocvd

摘要

The adsorption, diffusion, and dissociation of precursor species, MMGa (monomethylgallium) and NH_3, on the GaN (0001) surface have been investigated using the DFT (density functional theory) calculation combined with a GaN (0001) surface cluster model. The energetics of NH_3(ad) dissociation on the surface proposed the dissociation of NH_3(ad) via NH_2(ad) to NH(ad) was facile with small activation barriers. A combined analysis with surface diffusion of adatoms demonstrated Ga(ad) and NH(ad) become primary reactant species for 2D film growth, and N(ad) develops into a nucleation center. Our studies suggest the control of NH_3(ad) dissociation are essential to improve epitaxial film quality as well as Ga-rich condition. In addition, the adsorbability of H(ad)s resulted from NH_3(ad) dissociation were found to influence on the surface chemistry during film growth.