THERMAL ROUGHENING OF UNCORRELATED STEPS

We study the thermal roughening of uncorrelated step edges on vicinal face centred cubic (lll) surfaces by means of kinetic Monte Carlo (MC) simulations and kinematic calculations of the diffraction profiles. B oth the Initial and the final local atomic environments are used in th e MC model to determine the hopping probability for atoms diffusing on the surface. We found that the step-edge fluctuations are Gaussian di stributed when the kink density has saturated. Deviations from the Gau ssian distribution are present early on because of the straight edge i nitial configuration. Deviations from the Gaussian distribution is als o expected when the overall equilibrium over the whole surface has bee n established. We discuss the shapes of the resulting terrace distribu tions. (C) 1997 Elsevier Science B.V.