Annealing temperature effect on the structural, optical and electrical properties of ZnS thin films

Zinc sulfide thin films were prepared on glass substrates at room temperature using a chemical bath deposition method. The obtained films were annealed at temperatures ranging from 100 to 500 degrees C in steps of 100 degrees C for 1 h. The films were characterized by X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray analysis (EDX), optical absorption spectra, and electrical measurements. X-ray diffraction analysis indicates that the deposited films have an amorphous structure, but after being annealed at 500 degrees C, they change to slightly polycrystalline. The optical constants such as the refractive index (n(r)), the extinction coefficient (k), and the real (epsilon(1)) and imaginary (epsilon(2)) parts of the dielectric constant are calculated depending on the annealing temperature. Aside from the ohmic characteristics of the I-V curve, a nonlinear I-V curve owing to the Schottky contact is also found, and the barrier heights (phi(bn)) for Au/n-ZnS and In/n-ZnS heterojunctions are calculated. The conductivity type was identified by the hot-probe technique. (C) 2010 Elsevier B.V. All rights reserved.