Theory of optical reflectance anisotropy of the natural Si(110) surface

We investigate theoretically the optical reflectance anisotropy of the natural Si(110) surface, including the surface intrinsic anisotropy and the surface local-field effect. We model a rough Si(110) surface, determining a number of defect structures by total-energy minimization. We show that a structure with missing Si atoms and partial H coverage gives a reflectance anisotropy in agreement with experiment, in contrast to previous calculations for the ideally H-terminated Si(110) surface. We show that both the intrinsic anisotropy and the surface local-field effect are essential for such an agreement.