Anisotropy in periodic mesoporous silica and organosilica films studied by generalized ellipsometry

Abstract

The dielectric functions of a series of periodic mesoporous silica as well as periodic mesoporous organosilica thin films were measured using generalized variable angle spectroscopic ellipsometry over the spectral range 300–1400nm. Ellipsometry results indicate that following template removal, both types of films possess uniaxial anisotropy, with the optic axis perpendicular to the plane of the film. This anisotropy is apparently caused by the structural distortion of the channels, oriented primarily parallel to the substrate plane. We also find that the birefringence increases as a function of porosity.