STRAIN DEPENDENCE OF BINDING-ENERGIES FOR CARBON ADATOMS ON THE SI(100) SURFACE

Calculations were carried out to analyze the strain dependence of the binding energy of a carbon adatom deposited on a (2 x 1) dimerized Si( 100) surface. Two different low energy binding sites on the reconstruc ted Si(100) surface were taken into consideration. The lowest energy s ite is located near the top position of a second layer Si atom; while the second lowest energy site is at the bridge site between two top la yer Si atoms forming the dimer. Results indicate that the binding ener gy for a carbon atom adsorbed in the lowest energy sites is affected m ost by the esxternal strain. In particular, the effect of a uniaxial s train applied in the direction perpendicular to the surface Si dimers, was found to be quite significant. While a tensile stress in this dir ection produces an increase in the value of the binding energy, a comp ressive strain was found to lower the binding energy. In general, stra ins applied in the direction parallel and perpendicular to Si dimers w ere found to produce opposing effects on the binding energies.