Structural and optical properties of Ag2S thin films prepared by spray pyrolysis

Silver sulphide Ag2S thin films have been prepared on pyrex glass substrates by the spray pyrolysis technique using silver acetate and thiourea as starting materials. The depositions were carried out in the range of substrate temperatures from 100 to 300 degrees C. Measurements of X-ray diffraction show that the deposited layers at 250 degrees C mere well crystallized and oriented preferentially in the direction (<(1)over bar 03>). Films surfaces were analysed by contact Atomic Force Microscopy (AFM) in order to understand the effect of the deposited temperature on the surface structure. On the other hand, from transmission and reflection spectra, the band gap energy determined is about 1.14 eV. In the same way, an iterative method based on the optical reflectance and transmittance of Ag2S thin film prepared at 250 degrees C were used to obtain the refractive index and the extinction coefficient. Their values vary in the wavelength range 640-2200 nm from 2.38 to 2.81 and from 0.001 to 0.277 respectively.