Tailoring optical and electrical properties of ternary Pb_1−xCo_xS thin films synthesized from a combination of two complexing agents

Chemical bath deposition technique was used to synthesized Pb_1−xCo_xS compounds at a bath temperature of 75 °C by using double complexing agents. The thin films were characterized by varies of techniques. The XRD study confirmed that all the prepared thin films had face-center cubic crystal structure and the crystalline oriented along the (111) plane irrespective of cobalt concentrations. The XRD results further revealed that cobalt incorporation had a considerable effect on the intensity and position of the diffraction peaks. The SEM and HRTEM analyses justified that the surface morphology of Pb_1−xCo_xS thin films was strongly dependent on the amount of the dopant. The presence of Co, S and Pb elements in the prepared compounds was established by the EDX analyses. The UV–Vis study demonstrated that the band gap values of Pb_1−xCo_xS films engineered from 0.80 to 1.50 eV by varying cobalt doping concentrations. Furthermore, the refractive index, dielectric constant and linear optical susceptibility were calculated using the energy band gap values. The dc-two point probe measurement verified that the electrical properties of the Pb_1−xCo_xS thin films were considerably changed by the cobalt doping concentrations and the thermal activation energies were found in the range of 0.587–0.976 eV. (author)