Preparation and Characterization of SnS:Bi Thin Films

Thin films based on Sn-S compounds are currently of great interest because of their potential applications in optoelectronic devices including solar cells. In this work, SnS:Bi thin films are prepared using a novel procedure based on sulfurization of their metallic precursors, varying the Bi content. The effect of the synthesis conditions on the optical properties, phase, and chemical composition of the SnS:Bi thin films was studied through spectral transmittance, X-ray diffraction, and X-ray photoelectron spectroscopy. It was established from transmittance measurements that the optical gap of the deposited films varies between 1.27 and 1.37 eV depending on the Bi content. The analysis revealed that the SnS:Bi thin films grow with a mixture of several phases which include SnS, Sn₂S₃ SnS₂, and Bi₂S₃, depending on the Bi concentration. The studies also revealed that the conductivity type of the SnS:Bi films depends on the Bi content in the SnS lattice.