Ellipsometry and the clean surfaces of silicon and germanium

The anomalous ellipsometric effects, which occur upon chemical adsorption of gases on clean silicon and germanium surfaces have been determined in the wavelength region 0.34–1.8 μm. The effects are ascribed to the removal of a transition layer with optical constants different from the crystalline bulk values. Within the scope of this model the optical constants of the transition layer proved to be similar to those of the corresponding amorphous materials. The differences in optical constants between crystalline material on the one hand and amorphous material and transition layer on the other, could be attributed to the presence of dangling or distorted bonds.