Investigation on post annealed copper sulfide thin films from photochemical deposition technique

CuxS thin films were deposited on glass substrates at room temperature by photochemical deposition after 1 h photo irradiation using the precursor solution containing copper sulphate pentahydrate (CuSO4·5H2O), sodium thiosulphate (Na2S2O3) as a source material for Copper and Sulphur respectively and Di Sodium salt of EDTA as a chelating agent in acidic medium (pH~3.0). The as deposited and annealed CuxS thin films were investigated using XRD, UV–vis, AFM, SEM and Hall measurements. The deposited thin films were annealed at temperature up to 400 °C for 1 h. Above 200 °C the deposited film of CuxS changes from anilite phase (Cu1.75S) to digenite (Cu1.8S) phase. The reduction in sulphur content of the films is evident in the EDX analysis. From the Hall Effect results as deposited and annealed films show p-type conductivity with increasing bulk concentration. Analyses of the optical bandgap of the films indicate an indirect bandgap between 1.75 and 2.35 eV.