Spectroscopic ellipsometry studies on ferroelectric surfaces

Summary form only given. Spectroscopic ellipsometry offers a means through which it should be possible to nondestructively characterize both intrinsic and processing-induced surface layers throughout a proposed thickness regime. Measurements of the ellipticity and azimuth of the reflected light were made between 300 and 700 nm using a xenon source with a rotating analyzer ellipsometer. A large BaTiO₃ crystal oriented with the optic axis perpendicular to the surface was polished in steps down to 0.05-μm grit. After poling to remove 90° domains, ellipsometric data were collected at four angles of incidence. Several models for the surface region were examined by fitting all data sets simultaneously. The best fit, chosen using a nonlinear regression analysis, was for a layer approximately 140 angstrom thick with a refractive index considerably below those shown by bulk BaTiO₃.