Anisotropies in the Above—Band-Gap Optical Spectra of Cubic Semiconductors

We report the first systematic study of above---band-gap optical anisotropies in cubic semiconductors. The anisotropies are large, of the order of 1%. The dominant intrinsic contributions for (110) Si and Ge are due to surface many-body screening and bulk spatial dispersion. Extrinsic contributions from chemisorbed and physisorbed species also play important roles.