Boron segregation on a vicinal Si(100) surface

Energetics of boron on a Si(100) stepped surface has been studied quantum mechanically at semi-empirical level. The step is represented by a cluster of silicon atoms and the boron impurity is moved in the step in substitutional and interstitial positions. The optimal configuration of the step with the impurity is evaluated from the minimization of the total energy. It has been found that, similarly to the known behavior in the flat surface, the boron impurity segregates below the surface. However the preferred adsorption sites have also a remarkable dependence on the distance from the step-edge. We illustrate the dependence of these sites on the step geometry.