HF-Treated (111), (110) and (100)Si Surfaces Studied by Spectroscopic Ellipsometry

Spectroscopic ellipsometry (SE) has been used to study chemical (or structural) differences in HF-treated Si surfaces with three different crystallographic orientations, (111), (110) and (100). The observed orientation-dependent SE data are tentatively explained in terms of two causes: the differences in the H-terminated Si (dangling bond) densities and the degree of surface roughness produced by the HF treatment. The HF-treated Si surfaces are also found to become hydrophobic if the surface oxides are completely removed. However, no clear orientation dependence of the wettability has been found among these surface orientations.