EQUILIBRIUM STEP DYNAMICS ON VICINAL SURFACES

The time tau necessary for the formation of bumps due to thermal fluct uations on steps of vicinal surfaces is evaluated in various relevant cases. Formulae already derived by Mullins and Bales and Zangwill and other expressions recently published by Bartelt et al., are found as s pecial cases. For Si(111) at 900-degrees-C we predict that tau is prop ortional to the step-step separation l and to the square of the fluctu ation wavelength L. This prediction is found to be in reasonable agree ment with direct experimental observations of equilibrium step fluctua tions.