Influence of (7×7)-“1×1” phase transition on step-free area formation in molecular beam epitaxial growth of Si on Si (111)

The step-flow growth condition of Si on Si (111) near the (7×7)-“1×1” surface phase transition temperature TC is analysed within the framework of Burton-Cabrera-Frank theory. In particular, coexistence of both surface phases well below TC and their specific influence on the step-flow growth behaviour is considered. We presume that under dynamical condition of growth, the surface initially covered by only the (7×7) phase separates into domains surrounded by “1×1” areas. On such a surface, the overall supersaturation should be reduced drastically compared to a surface with only (7×7), resulting in much larger critical terrace width for nucleation.