Influence of the thickness on physical properties of chemical bath deposited hexagonal ZnS thin films

Abstract

Hexagonal ZnS thin films of thicknesses ranging between 454 to 750 nm are deposited on a glass substrate by chemical bath deposition at 80 °C. The ZnS thin films are characterized by X-ray diffraction (XRD) and optical absorption spectroscopy. The films are shown to be crystallized in the hexagonal phase and present a preferential orientation along the c-axis by XRD measurements . Only one peak, corresponding to the (008) phase (29=29.5°), appears on the diffractograms. The ZnS films show a high transmission. The optical constants such as refractive index n, extinction coefficient k, real ?1 and imaginary ?2 part of dielectric constant are calculated in the visible region. A reduction in refractive index (n) and the extinction coefficient (k) is observed as film thickness decreases. The electrical conductivity decreased from 1.62×10-9to 1.32×10 -10 (?.cm)-1 when the films are annealed at 400 °C for 1 hour. The temperature-dependent current was measured in the range 27-400 °C and the activation energy values were obtained using the temperature-dependent current measurements.