Chemically deposited Sn-doped PbS thin films for infrared photodetector applications

Lead sulfide is a potential infrared (IR) photodetector material because of its favorable optoelectronic properties. The physical and chemical properties of PbS can be modified by a systematic doping of elements. In this study, we have doped 1–3 at% of Sn into PbS by a chemical bath deposition method. The undoped PbS films exhibited cubic crystal structure with a lattice parameter of $$\hbox{a} = 0.594\,\hbox{nm}$$ , an uneven grain growth, a direct optical band gap of 0.44 eV and a hole mobility of $$8.9\,\hbox{cm}²\,\hbox{V}^-1\,\hbox{s}^-1$$ . The Sn-doping has improved the microstructure and slightly decreased the band gap of PbS. The hole mobility of PbS films has increased to $$20\,\hbox{cm}²\,\hbox{V}^-1\,\hbox{s}^-1$$ with Sn-doping (1–2 at%). Thus, the PbS films grown by Sn-doping with improved microstructure, decreased band gap, and increased electrical properties are beneficial for IR photodetector applications.