Leem determination of critical terrace widths for Si/Si(111) step flow growth

The condition for step flow growth of Si on the Si(111)-(7 × 7) surface has been investigated using low energy electron microscopy (LEEM). The critical terrace width for step flow growth was found to be independent of the azimuthal direction. This is consistent with isotropic diffusion and step flow kinetics. The dependence of the critical terrace width upon temperature for fixed incident flux (0.1 monolayer/minute) has also been measured. The square of the critical terrace width exhibits an Arrhenius behavior between 750 and 850 K with prefactor A = 7.0 × 10¹⁹ nm² and activation energy E = 2.05 eV. These values are significantly larger than those determined by Iwanari et al. [J. Cryst. Growth 119, 241 (1992)] at lower temperatures and similar flux. Possible origins of this discrepancy, including the validity of the Arrhenius description, are discussed.