Thermally stimulated currents in ZnS sandwich structure deposited by spray pyrolysis

Polycrystalline ZnS semiconducting films have been prepared in sandwich configuration by spray pyrolysis technique using ZnO-coated glass substrates and mixed aqueous solutions of ZnCl2 and thiourea. The sandwich structures have been produced successfully by means of ZnO-coated glass substrates. The produced ZnS films have been crystallized in a wurtzite structure and had a direct band gap energy of 3.62 eV. The electrical properties of the sample have been studied by an analysis based on the thermally stimulated current spectra in the temperature range of 40-300 K with various heating rates. A set of curves of I (T) for varying initial density of filled traps at a heating rate of β2=0.06 K s−1 indicate that the observed peaks in the TSC curve of polycrystalline ZnS films have first-order features. In order to evaluate the trap parameters of ZnS films, we have used curve-fitting method. The values of the frequency factor ν, the capture cross section S and the concentration of the traps have been determined for three first-order peaks in the TSC spectrum of ZnS.