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° 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° 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.