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

Abstract 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 °C in steps of 100 °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 °C, they change to slightly polycrystalline. The optical constants such as the refractive index ( n r ), the extinction coefficient ( k ), and the real ( e 1 ) and imaginary ( e 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 ( ϕ bn ) for Au/n-ZnS and In/n-ZnS heterojunctions are calculated. The conductivity type was identified by the hot-probe technique.