Structure, optical, and photoelectric properties of lead-sulfide films doped with strontium and barium

The morphological evolution of composition, structural characteristics (lattice constant, microdeformations, texturing), optical and photoelectric properties of PbS films obtained by chemical bath deposition in the presence of ammonium iodide and strontium/barium chlorides at a concentration range up to 5 mmol/l was studied. According to elemental EDX analysis, the strontium content in PbS films was 0.4–0.7 at%, whereas barium concentration was beyond the determination error interval. The size of the particles forming the PbS films ranged from $\sim$200 to $\sim$400 nm with monomodal particle size distribution. The introduction of NH$_{4}$I and SrCl$_{2}$ or BaCl$_{2}$ into the bath retained the cubic B1 structure of PbS films, but led to a nonmonotonic change in the lattice parameter, which was associated with the defects, namely, vacancies or interstitial ions. The introduction of strontium and barium salts had no effect on the PbS band gap, but led to a change in the intensities of the impurity absorption bands in the depth and near the bottom of the conduction band. The dependence of the volt–watt sensitivity of the PbS films upon the concentration of strontium/barium in the solution was extreme with maxima at 0.05 and 0.1 mmol/l, respectively.