Effect of vacuum annealing on structural, optical and magnetic properties of Sn doped ZnS thin films

Tin doped Zinc Sulphide (Zn1-xSnxS) thin films at x = 0.00, 0.02, 0.05, 0.08 were prepared onto Corning 7059 glass substrates using electron beam evaporation technique and then subjected to vacuum annealing at 300 C for 2 h. The effect of vacuum annealing on structural, optical and magnetic properties of the thin films were studied in detail. From XRD studies, it was found that the vacuum annealed thin films were in cubic structure and have finer crystallite size compared to the unannealed thin films. All the films exhibited high transmittance (85%) in the visible region. The vacuum annealing led to narrowing of band gap compared to the unannealed thin films. The presence of surface defects in vacuum annealed thin films were confirmed by the observation of two broad emission photoluminescence peaks at 420 nm and 440 nm. But the reduction in the intensity of photoluminescence emission peaks correlate to the decrease in the concentration of sulphur vacancies. Also, the vacuum annealed Sn doped ZnS thin films were found to exhibit paramagnetic behaviour with lesser maximum magnetization value compared to that of the unannealed Sn doped ZnS thin films.