Deposition Time-dependent Study of Structural and Optical Properties of PbS Thin Films Grown by CBD Method

Background: Thin films of PbS were prepared onto glass substrates by using a simple and cost-effective CBD method. Methods: The influence of deposition time on structural, morphology and optical properties have been investigated systematically. The XRD analysis revealed that PbS films are polycrystalline with preferred orientation in (200) direction. Enhancement in crystallinity and PbS crystallite size has been observed with an increase in deposition time. The formation of single-phase PbS thin films has been further confirmed by Raman spectroscopy. The surface morphology analysis revealed the formation of prismatic and pebble-like PbS particles and with an increase in deposition time, these PbS particles are separated from each other without secondary growth. The data obtained from the EDX spectra show the formation of high-quality but slightly sulfur-rich PbS thin films over the entire range of deposition time studied. Results and Conclusion: All films show an increase in absorption with an increase in deposition time and strong absorption in the visible and sub-bandgap regime of the NIR range of the spectrum with red-shift in band edge. The optical band gap shows a decreasing trend, as deposition time increases but it is higher than the bandgap of bulk PbS.