Ab initio study of epitaxial growth on stepped Si(100) surface

Abstract

Ž .Diffusion of a Si adatom over the reconstructed Si 100 surface with a single-height step on it is studied using the pseudopotential total energy method. The S rebonded step is B shown to act as a good sink for adatoms descending onto the lower ledge. This is due to the presence of deep traps on the lower terrace and to the negative Ehrlich᎐Schwoebel Ž 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. However, the dimer buckling sequence on a lower terrace is strongly dependent on the position of the adatom along the diffusion path.

First-principles calculation of the effect of strain on the diffusion of Ge adatoms on Si and Ge (001) surfaces

“…Since a typical surface consists of terraces where the direction of the dimer rows changes by 90 • at each monoatomic step, fast diffusion in any direction is possible at the mesoscopic level, even though the fast diffusion is unidirectional at the microscopic level. Earlier studies 24,25,26,32 have unambiguously determined the location of the binding site and the activated state of the Ge adatom on the Si (001) surface (see Fig. 1) as well as the precise configuration of the surface dimers in the vicinity of the adatom.…”

“…This artificial periodicity is harmless, provided that convergence with respect to the distance between the periodic images is achieved. Following earlier studies of adatom diffusion of similar systems, 24,25,26 our supercell consists of two repetitions of the surface unit cell, depicted in Fig. 1 along the dimer rows direction (i.e.…”