Effect of molar concentration of CuCl2 on the characteristics of Cu2S film

In this work, the influence of molar concentration of CuCl 2 on copper sulfide Cu 2 S film synthesized by chemical bath deposition and on the performance of p-Cu 2 S/p-Si heterojunction photodetector was studied. The effect of copper chloride concentration on the structural, optical properties and electrical properties of Cu 2 S film was investigated. The optical studies show that the optical energy gap varied from 2.68 to 2.8 eV as the concentration varied from 0.06 to 0.15 M. X-ray diffraction XRD results confirm that the deposition films having of monoclinic chalcocite phase. Scanning electron microscope SEM investigation illustrate the formation of nanostructured Cu 2 S film with particle size ranged from 50 to80 nm depending on the copper chloride concentration. Two Raman peaks were observed located at 265 and 470 cm −1 assigned to the Cu–S bond vibration and vibrational stretching mode, respectively. The mobility of charge carriers in the film and the electrical conductivity of the film were investigated as a function of copper chloride concentration. Dark and illuminated I-V characteristics of p-Cu 2 S/p-Si heterojunction HJ photodetectors were measured at room temperature. The best rectification was for heterojunction prepared at 0.13 M CuCl 2 . The maximum responsivity of the photodetector was about 0.67A/W at 450 nm for photodetector prepared at 0.13 M.