WETTING OF LATERALLY STRUCTURED SURFACES

An x-ray scattering study of a laterally structured solid surface wett ed by a liquid is reported. GaAs (001) samples with etched trapezoidal surface gratings are used as substrates. Due to the lattice spacing o f d = 5900 angstrom and the height h of about 450 angstrom such gratin gs can be regarded as a row of free edges and wedges. The special wett ing behaviour of these wedges with a liquid film of CCl4 was studied u sing x-ray reflectivity in the region of total external reflection. Th e reflectivity of the film on top of the laterally structured GaAs sub strate is explained by model calculations which contain the electron d ensity depth profile perpendicular to the surface. The thickness of th e liquid wetting film on top of the stepped surface was obtained from the fit of the data.