Carbon-doped Sb2S3 thin films : Structural, optical and electrical properties

We report the modification of electrical properties of chemical-bath-deposited antimony sulphide (Sb2S3) thin films by thermal diffusion of carbon. Sb2S3 thin films were obtained from a chemical bath containing SbCl3 and Na2S2O3 salts at room temperature (27 deg C) on glass substrates. A carbon thin film was deposited on Sb2S3 film by arc vacuum evaporation and the Sb2S3-C layer was subjected to heating at 300 deg C in nitrogen atmosphere or in low vacuum for 30 min. The value of resistivity of Sb2S3 thin films was substantially reduced from 108 Omega cm for undoped condition to 102 Omega cm for doped thin films. The doped films, Sb2S3:C, retained the orthogonal stibnite structure and the optical band gap energy in comparison with that of undoped Sb2S3 thin films. By varying the carbon content (wt%) the electrical resistivity of Sb2S3 can be controlled in order to make it suitable for various opto-electronic applications.