Optimization of the synthesis and characterizations of chemical bath deposited Cu2S thin films

Abstract

Semiconducting copper sulphide (Cu 2 S) thin films have been deposited on various substrates (SnO 2 :F/glass, glass) by the simple and economical chemical bath deposition technique. The depositions were carried out during a deposition time of about 32.5 min in the pH range of 9.4 to 11. The synthesized Cu 2 S thin films were characterized using various techniques without any annealing treatment. X-ray diffraction study shows that Cu 2 S films exhibit the best crystallinity for pH = 10.2. For this pH value, Auger electron spectroscopy investigations show that Cu 2 S thin films grown on an SnO 2 /glass substrate exhibit stochiometric composition with [Cu]/[S] concentrations ratio equal to 2.02. Using the Kelvin method, the work function difference ( Ф material – Ф probe ) for the Cu 2 S films deposited on SnO 2 /glass substrates at the optimum pH value was found to be equal to 145 meV. Hall measurements confirm the p-type electrical conductivity of the obtained films. The electrical resistivity was of the order of 3.85 × 10 −4 Ω-cm. The transmission and reflection coefficients vary in the range of [35–60] % and [5–15] % respectively, in the visible range, and the band gap energy is about 2.37 eV.