Generalized ellipsometry for monoclinic absorbing materials: determination of optical constants of Cr columnar thin films.

Generalized spectroscopic ellipsometry is used to determine the form-induced birefringence and monoclinic optical constants of chromium columnar thin films. The slanted nanocolumns were deposited by glancing angle deposition under 85 degrees incidence and are tilted from the surface normal. Dichroism measured for wavelengths from 400 to 1000 nm renders the Cr nanocolumns monoclinic absorbing crystals with c axis along the nanocolumns axis, b axis parallel to the film interface, and 74.8 degrees monoclinic angle between a and c axes. The columnar thin film reveals anomalous optical dispersion, extreme birefringence, and strong dichroism and differs entirely from bulk chromium.