Spirals on Si(111) at sublimation and growth: REM and LODREM observations

Using recently proposed improvements of reflection electron microsopy (REM) we study, in perfectly controlled thermodynamics conditions, spiral and spirals shapes on Si(111) surface. It is shown that the new method named low distortion reflection electron microscopy (LODREM) is a powerful instrument, resolving in much more details (compared with REM) growth or evaporation spirals at the crystal surface. More precisely, we examine the distance between two successive steps of a spiral at growth (or evaporation) with respect to the supersaturation (or undersaturation). It is found that this distance scales with an exponent close to 1/2. This result, which deviates from the BCF theory, originates from a non-local behavior with a slow kinetic of attachment of the adatoms at the steps. 2006 Elsevier B.V. All rights reserved.