The transmittance (T) of thin films of CdI2, prepared by thermal
evaporation technique on quartz substrates,
have been measured over the wavelength range 200−900 nm. From
analysis of the transmittance data, the optical constants, the
refractive index (n) and the extinction coefficient (k), have
been studied. Analysis of the refractive index (n) yields a low
frequency dielectric constant, average oscillator strength and
average oscillator energy. From analysis of the absorption
coefficient (α), the fundamental absorption edge can be
determined. Both allowed direct transitions and allowed indirect
transitions are observed. The composition of films is checked
using energy dispersive X-ray (EDX) spectroscopy technique. X-ray
diffraction (XRD) measurements showed that the CdI2 films
evaporated at room temperature substrates were characterized by a
polycrystalline form. At large thicknesses the films indicated the
inhomogeneity. The effect of annealing temperature (up to 523 K) on
the film properties has been studied.