Kinetic length and step permeability on the Si(111) (1 x 1) surface

Information on the kinetic regime of step motion and step permeability on the Si(I 11) (1 x 1) surface has been obtained from observations of island decay that were made with low energy electron microscopy. Island area during decay exhibits the expected power law dependence on time, with exponent, a, that is a qualitative indicator of the kinetic regime. A new method is presented for determining the kinetic length quantitatively from measurements of the decay exponent in the symmetric island decay geometry on top of a larger concentric circular island. Using this approach, we determine the kinetic length on the Si(l 11) (1 x 1) surface at 1163 K to be d similar to 75a, where a is the lattice constant. It is shown that this result locates step motion firmly in the diffusion limited regime. Mass conservation of decaying island stacks is also observed at this temperature, which indicates that steps are effectively impermeable in the context of diffusion limited step kinetics. (c) 2007 Elsevier B.V. All rights reserved.