Kinetic length, step permeability, and kinetic coefficient asymmetry on the Si(111) (7x7) surface

The island nucleation position at the critical terrace width for step flow on the Si(111) (7x7) surface has been measured with low-energy electron microscopy. These data allow for the kinetic length, which is indicative of the rate-limiting step, to be evaluated and provide compelling new evidence that steps are impermeable. The assessment of step kinetic coefficient asymmetry and its potential for effecting growth instabilities depends crucially upon the kinetic length and step permeability. Step attachment is found to be favored from the terrace trailing an advancing step.