Surface-induced optical anisotropy of Si and Ge

Abstract

We compare surface-induced optical anisotropy spectra measured by reflectance difference/anisotropy spectroscopy of Si and Ge. Our previous work on Si has shown that we can roughly distinguish two types of contributions to the optical response of surfaces: direct contributions involving surface state transitions and indirect contributions in which the surface modifies the bulk response. We demonstrate here that this view is valid for Ge as well. For Si the indirect surface contributions exhibit three extreme, basic line shapes, which are all related to the bulk dielectric function εb or nanostructured material. We demonstrate that this line shape analysis can also be applied to Ge.