Binding Sites, Migration Paths of an Sb Adatom on the Si (111) Surface

Hwa-Suck Cho (Dept. of Physics, Yeungnam University, Kyungsan, 712-749, Korea), J. H. Park (Dept. of Physics, Yeungnam University, Kyungsan, 712-749, Korea) and T. P. Das (Dept. Physics, SUNY at Albany, Albany, NY, 12222)

We have performed first-principle calculations of the potential energy surface for the binding and migration of a Sb atom on the Si (111) surface. The use of group V elements as surfactants at semiconductor heterojunction interfaces in the epitaxial growth, has prompted the study of adsorption of Sb on Si and Ge surfaces. A monolayer of Sb deposited on the (111) surface of Si helps in the growth of low defects films of Ge on top of the Si substrate. We used a Sb deposited Si (111) structure with one Sb atom and four Si layers to model the Si (111)-(7x7) surface. The most stable adsorption site of a single Sb adatom has been confirmed to be the T4 site, and the Sb adsorption on the H3 site the next stablest. In order to determine the probable Sb migration path on Si (111) surface, the potential energy of Sb adatom has been calculated as a function of position, with the shortest path connecting the T4 sites found to be the most likely one for Sb diffusion at low coverages.

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