Optical, Morphological and Electrical Properties of PBS Thin Films Prepared by Chemical Bath Deposition (CBD) Technique at Different Deposition Time

Abstract

Abstract Lead sulphide (PBS) thin films have been investigated in this present work by using chemical bath deposition (CBD) technique onto glass substrates with different deposition times (20, 40 and 60 min.) at 70oC (158oF) exploiting lead nitrate and thiourea as lead and sulphide ions sources. The effect of the deposition time on the optical, morphological and electrical properties of the as-deposited PBS films were studied. The thin films exhibit a strong optical absorption in the ultraviolet (UV) and visible regions but low absorption over the longer wavelength region towards near infrared (NIR) of the electromagnetic spectrum. In contrast, the films transmit very low at the UV and visible regions while NIR region exhibit a good optical transmission. The optical band gap energy of the films decreases with increase in deposition time ( D t ), ascribing larger particle size. The extinction coefficient (k) of the films increased with deposition time increment which corresponds to greater attenuation of light and also the higher probability of raising the electron transfer across the mobility gap with the photon energy. The image obtained shows almost dense spherical and uniform grains with an increase in time of dipping the glass slides into the solution. The electrical conductivity was observed to be inversely related to the optical band gap energy of the films.