Structural and functional features of photoactive lead sulfide films with iodine-containing impurity phases

The lead sulfide films obtained by the chemical bath deposition from the solutions contained KMnO₄, NH₄I or their combination are studied. The kinetic studies of the transformation of lead salt into sulfide under conditions of spontaneous nucleation of the solid phase show the inhibitory effect of the additives the rate of the process and resulting in a decrease of the thickness of PbS films from 640 to 370 nm. A comprehensive analysis of the composition, morphology and structure of the synthesized layers was carried out using scanning electron and atomic force microscopy, energy dispersive analysis, Auger spectroscopy and X-ray diffraction. The average content of the main elements Pb, S, I, O in the films and their distribution over the thickness were established. From the features of changes in the lattice parameter, crystallographic orientation, the magnitude of microdeformations, internal microstresses, and coherent scattering regions, the “critical” character of concentration of KMnO₄ equal to 1 mM was revealed. From measurements of the Raman and infrared transmission spectra, the formation of I₂O₅ or I₂O₄ on the surface of the films is found. A synergistic effect of the combination of KMnO₄ and NH₄I in reaction bathes caused by the formation of photoactive phases of iodine oxides and resulting in increasing the voltage sensitivity of PbS films synthesized has been revealed.