Photochemical deposition of Cu xS thin films from aqueous solutions

Abstract

Cu x S thin films were deposited on indium–tin–oxide-coated glass substrates by photochemical deposition from an aqueous solution of CuSO 4 and Na 2S 2O 3. Thin films of different compositions of Cu x S 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 Cu x S thin films. The optical spectra of Cu x S films exhibit high transmission in the visible region and absorption throughout the near-infrared region (800–1500 nm). The energy band gap of Cu x S films was estimated in the range of 2.15–2.53 eV.