KINETIC ROUGHENING OF SI SURFACES AND SURFACTANT EFFECT IN LOW-TEMPERATURE MOLECULAR-BEAM EPITAXY GROWTH

Thanks to an experimental (in situ reflection high-energy electron dif fraction and ex situ high-resolution electron microscopy) and a theore tical probabilistic cellular automaton study of surface kinetic roughe ning in low temperature silicon molecular beam epitaxy, we achieve a c lear correlation between the surface roughness and the microscopic mor phology of the growing layer. A transition in the growth mechanisms be tween a perfect epitaxy regime and another one displaying structural d efects is shown. It may explain previous unusually observed deviations of the surface roughness scaling behavior unpreviewed by current theo ries. The effect of gallium atoms as ''surfactants'' is also investiga ted. High-resolution electron microscopy comparison of layers grown wi th and without gallium shows its role in the surface morphology smooth ing. (C) 1998 American Vacuum Society.