Structure, Optical, and Photoelectric Properties of Lead-Sulfide Films Doped with Strontium and Barium

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Evolution of the morphology, composition, structural characteristics (lattice constant, microstrains, texturing), and optical and photoelectric properties of PbS films produced by chemical bath deposition in the presence of ammonium iodide and strontium or barium chlorides at a concentration up to 5 mM is studied. According to the data of energy dispersive X-ray analysis, the content of strontium in the PbS films is 0.4–0.7 at %, whereas the content of barium is beyond the determination error. The size of the particles forming the films varies from ~200 to ~400 nm, and the size distribution of the particles is monomodal. The introduction of NH4I and SrCl2 or BaCl2 into the reactor retains the B1 cubic structure of lead sulfide, but gives rise to an unsteady change in the lattice parameter, which is due to the creation of vacancy-type or interstitial ion defects. The introduction of salts of strontium or barium does not influence the band gap, but changes the intensities of the impurity absorption bands deep in the band gap or near the bottom of the conduction band. The dependences of the volt–watt sensitivity of the films on the content of salts of strontium and barium are of an extreme character and show maxima at 0.05 and 0.1 mM, respectively.