Investigation on the optical properties of ZnS nano-rod and chiral sculptured thin films using experimental and theoretical approaches

Abstract

ZnS thin films with nano-rod and chiral sculptured structures of different thicknesses were deposited on glass substrates. Nano-structure of the films was obtained, using field emission scanning electron microscopy (FESEM). Their optical properties were measured by spectrophotometry in the spectral range of 350–1000 nm for both s- and p-polarizations at different incident light angles. The concept of local homogenization proposed by Bruggeman is used by estimating the permittivity dyadics of ZnS in the form of thin films with nano-rod and chiral sculptured structures. Making use of a simulation program, the influence of different deposition parameters on the optical spectra of the above-mentioned sculptured thin films is investigated. It is found that film thickness plays a major role in affecting the optical spectra of thin films and variation of other parameters results in a shift in the position (wavelengths) of the peaks. It is shown that the simulation results may be used for prediction of optical spectra of these sculptured thin films and can particularly be useful in the case of chiral sculptured thin films whose production can be a cumbersome task.