Ab Initio Study of Expitaxial Growth on a Si(100) Surface in the Presence of Steps

Abstract

AbstractThe motion of a Si adatom over the reconstructed Si(100) surface with single-height rebonded (SB) step is studied using the pseudopotential total energy method. The step is shown to act as a good sink for adatoms descending onto the lower ledge. This is due to the presence of deep traps at the rebonded dimer row on the lower terrace and to the negative Ehrlich-Schwoebel barrier (the activation barrier for descent from the edge is 0.23 eV lower than for the motion on a flat surface). The diffusion characteristics of the adatom on both terraces are virtually unaffected by the presence of the step. The dimer buckling sequence on a lower terrace depends strongly on the position of the adatom along the diffusion path.