Structure and properties of PbS films

• PbS films prepared by chemical deposition from aqueous solutions have a D03-type crystal structure.
• This structure differs from the conventional cubic B1-type structure.
• Adjusting chemical deposition conditions, one can produce PbS films with a tailored particle size.
• Decreasing of average size of nanoparticles in PbS films leads to increasing of energy band gap.

The crystal structure of thin lead sulfide (PbS) films prepared by chemical deposition from aqueous solutions on a glass substrate is studied by X-ray diffraction analysis. It is established that the PbS films studied have a cubic (space group Fm3¯m) D03-type crystal structure different from the B1-type structure. Electron microscopic investigation of a film microstructure has shown that about half of all particles have a size of 60 nm and less. In the wavelength range from 300 to 3200 nm the optical transmission of PbS nanostructured cubic films with D03 structure and thickness from ∼120 to ∼400 nm is measured. Decreasing of average size of nanoparticles in PbS films leads to increasing of energy band gap Eg from 0.85 to 1.5 eV. These values of band gap are larger than that of coarse-grained PbS equal to 0.41 eV. It testifies on blue shift of the absorption band in studied nanostructured lead sulfide films.

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