Production and characterization of Ag doped ZnSe thin films

In this study; structural, electrical and optical properties of Ag-doped ZnSe thin films, unannealed and annealed at 500°C, were investigated by temperature-dependent Hall Effect, XRD, SEM-EDS, AFM and optical absorption measurements. In the first stage, ZnSe:Ag polycrystalline sample in ingot form was obtained from Zn and Se elements doped with 1% Ag by sinterization and grown on glass substrates by thermal evaporation (PVD) method. One of the thin films obtained was annealed at 500°C. As a result of the structural analyzes performed on the thin films grown by the PVD method, it was observed that the films were in cubic structure and changed to a more crystalline structure after annealing. Temperature-dependent electrical conductivity and Hall Effect measurements were made to determine the electrical properties of the samples. Due to the high resistance of the unannealed sample, electrical conductivity and Hall measurements could only be carried out for the annealed sample at 500°C. It was observed that the electrical conductivity of the films increased exponentially with increasing temperature. Two different activation energies were found from the current-voltage measurements of the films at different temperature ranges and these values were calculated as 21.03 meV in the 200-325 K range and 86.27 meV in the 325-375 K range. As a result of Hall measurements, the resistivity value was found as 1.23 × 10^4 (Ω.cm), Hall mobility as 5.19 × 10^1 (cm^2 V^-1 s^-1), carrier density as 4.22 × 10^12 (cm^-3) at room temperature. Hall measurements revealed that the carrier density increased with increasing temperature and it was determined that the sample was a p-type semiconductor. As a result of AFM analysis, the surface roughness of the unannealed sample decreased after annealing. The band gaps of the forbidden energy were examined in the range of 190-1100 nm with the UV/VIS spectrophotometer and it was determined that the band gaps decreased from 2.83 eV to 2.78 eV depending on the annealing.