Surface-induced optical anisotropy of Si and Ge

We compare surface-induced optical anisotropy spectra measured by reflectan ce difference/anisotropy spectroscopy of Si and Ge. Our previous work on Si has shown that we can roughly distinguish two types of contributions to th e optical response of surfaces: direct contributions involving surface stat e 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 El, or nanos tructured material. We demonstrate that this line shape analysis can also b e applied to Ge. (C) 2000 American Vacuum Society. [S0734-211X(00)08404-3].