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

Abstract

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 a = 0.594 nm, an uneven grain growth, a direct optical band gap of 0.44 eV and a hole mobility of 8.9 cm(2) V-1 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 cm(2) V-1 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.