Growth of SnS thin films by co-evaporation and sulfurization for use as absorber layers in solar cells

Tin sulfide thin films were grown by co-evaporation on soda-lime glass substrates. The synthesis was performed at different substrate temperatures between 200 degrees C and 400 degrees C at a growth rate of 6 angstrom/s, while adjusting the deposition time in order to obtain film thicknesses above 1500 nm. After evaporation, the samples were heated at 400 degrees C and 500 degrees C in sulfur atmosphere during 1 h. The evolution of the morphological, structural, optical and electrical properties has been analyzed as a function of the substrate temperature and the subsequent annealing. In the as-grown samples obtained at low temperatures, Sn tetragonal phase has been observed by XRD. By increasing the temperature up to 350 degrees C, the SnS phase started to form, the formation being completed at 400 degrees C. After sulfur annealing at 400 degrees C, all the samples evolved toward the SnS phase with band gap energy value around 1.22 eV. Otherwise, after annealing at 500 degrees C, it evolved towards SnS2 in the samples prepared at substrate temperatures above 300 degrees C. (C) 2015 Elsevier B.V. All rights reserved.