Photochemical deposition of CuxS thin films from aqueous solutions

CuxS thin films were deposited on indium-tin-oxide-coated glass substrates by photochemical deposition from an aqueous solution of CuSO4 and Na2S2O3. Thin films of different compositions of CuxS were deposited in acidic medium (pH ∼3.0) for the duration of 1-2 h photoirradiation. The thickness of the films was measured in the range of 0.15-0.35 μm. The as-deposited films were characterized by Auger electron spectroscopy (AES), X-ray diffraction (XRD), Raman spectroscopy and optical transmission spectroscopy. AES analysis showed a continuous copper-sulfur ratio x from 2.3 to 1.3 depending on the solution composition. Raman peaks were measured at about 475 cm−1. XRD studies showed polycrystallinity of the CuxS thin films. The optical spectra of CuxS films exhibit high transmission in the visible region and absorption throughout the near-infrared region (800-1500 nm). The energy band gap of CuxS films was estimated in the range of 2.15-2.53 eV.