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 x 7) surfac e has been investigated using low energy electron microscopy (LEEM). T he critical terrace width for step flow growth was found to be indepen dent of the azimuthal direction. This is consistent with isotropic dif fusion 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 exhib its an Arrhenius behavior between 750 and 850 K with prefactor A = 7.0 x 10(19) nm(2) and activation energy E = 2.05 eV. These values are si gnificantly larger than those determined by Iwanari et ad. [J. Cryst. Growth 119, 241 (1992)] at lower temperatures and similar flux. Possib le origins of this discrepancy, including the validity of the Arrheniu s description, are discussed.