Influence of calcium doping on structural, morphological and optical properties of chemically deposited PbS films

The calcium-doped PbS films are produced by using the chemical bath deposition method (CBD) on glass and sitall substrates. The influence of the calcium doping on the structural, morphological and optical properties of these films is studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical spectroscopy, and energy dispersive X-ray spectroscopy (EDX). The lead sulfide films have cubic structure (B1). The inclusion of calcium in the crystal structure of PbS up to 0.11 at. % is confirmed by the elemental, radiographic and energy-dispersive analyzes. The band gap Eg in the undoped PbS film is estimated as 0.40 ± 0.01 eV at 295 K and 0.38 ± 0.01 eV at 90 K and decreases with calcium doping by ∼0.02 eV. It is shown that doping of lead sulfide films with calcium by adding CaCl2 up to 5.0 mmol/l results in the increase in the photoresponse to IR radiation in 1.7 times.