Determination of optical birefringence by using off-axis transmission ellipsometry

Utilizing transmission ellipsometry at small angles of incidence, it is shown that c-cut uniaxial samples can be used to determine both the miscut of the optic axis with respect to the plane of incidence as well as very accurate values of the spectroscopic birefringence. For example, wafers of ZnO, LiNbO3, and 6H-SiC single-crystals are examined and the miscut direction and the spectroscopic birefringence are determined. While all materials show strong dispersion in birefringence, ZnO exhibits a distinct isotropic point at 396.8 nm.