Physical Property Characterization of Pb²⁺-Doped CdS Nanofilms Deposited by Chemical-Bath Deposition at Low Temperature

Pb^{2 +}-doped CdS nanofilms are prepared using the growth technique chemical bath deposition (CBD) under optimum conditions lead acetate at the reservoir temperature of 20 ± 2 °C. The Pb²⁺ molar concentration was in the range 0.0 ≤ x ≤ 0.19.67, which was determined by energy-dispersive X-ray spectroscopy (EDS). The X-ray diffraction results show that the films are of PbS–CdS composites with individual CdS and PbS planes. The X-ray diffraction (XRD) analysis and Raman scattering reveal that CdS-deposited films showed the zincblende (ZB) crystalline phase. The average grain size of the CdS films ranged from 1.21 to 6.67 nm that was determined by the Debye–Scherrer equation from ZB (111) direction, and it was confirmed by high-resolution transmission electron microscopy (HRTEM). Raman scattering shows that the lattice dynamics is characteristic of bimodal behaviour and the multipeaks adjust of the first optical longitudinal mode for the Pb²⁺-doped CdS denotes the Raman shift of the characteristic peak in the range of 305–298 cm⁻¹ of the CdS crystals, which is associated with the lead ion incorporation. The films exhibit three direct bandgaps, ~2.44 eV attributed to CdS; the other varies continuously from 1.67 to 1.99 eV and another disappears as Pb²⁺ molar fraction increases.