Inhibited Al diffusion and growth roughening of Ga-coated Al(100)

Ab initio calculations indicate that the ground state for Ga adsorption on Al(100) is on surface with local unit coverage. On Ga-coated Al(100), the bridge diffusion barrier for Al is large, but the Al --> Ga exchange barrier is zero: the ensuing incorporation of randomly deposited Al's into the Ga: overlayer realizes a percolation network, efficiently recoated by Ca atoms. Based on calculated energetics, we predict rough surface growth at all temperatures; modeling the growth by a random deposition model with partial relaxation, we find a power-law divergent roughness w similar to t(0.07+/-0.02).