Structural and optical properties of SnS semiconductor films produced by chemical bath deposition

SnS films have been deposited at room temperature by the chemical bath deposition technique. The films have been examined to evaluate their structure, morphology, composition and optical properties. SnS films were polycrystalline with an orthorhombic-herzenbergite structure. The lattice parameters and crystallite size of the sample have been calculated to be a = 4.39 angstrom, b = 11.17 angstrom, c = 3.97 angstrom with a/c = 1.106, and 67 nm, respectively. SnS films have been well crystallized in the form of cylindrical rods and the atomic ratio of Sn to S is 49.8 : 50.2. The optical properties of the sample have been studied using the transmittance and reflectance measurements as a function of wavelength between 190 and 3300 nm. The optical band gap is direct with a value of 1.31 eV. The refractive index and extinction coefficient as a function of wavelength for the film were investigated from the transmittance spectrum by applying the envelope method. The optical parameters of the material such as dielectric constants (n, k, epsilon(1) and epsilon(infinity)), plasma frequency omega(p) and carrier concentration N-opt were also evaluated.