THE INFLUENCE OF AN ELECTRIC-FIELD ON THE ELECTRONIC-STRUCTURE OF A SURFACE CONTAINING DEFECTS - AN EMBEDDING-POTENTIAL APPROACH

We study the effect of an idealized tip-induced electric field on the electronic structure of a semiconductor surface containing defects. Th e embedding-potential method is used to connect the Green's functions of the solid and the vacuum. The corresponding localized perturbation potential permits us to derive the Dyson equation for the Green's func tion of the full system. This equation is solved in real space on a di screte mesh. The polarization of the surface with defects is determine d inside the tunnelling barrier. It is found that the electronic densi ty over the clean surface responds more strongly to the tip-induced el ectric field than the electronic density over the region containing de fects.