Annealing effect on cadmium in situ doping of chemical bath deposited PbS thin films

This paper describes the effect of annealing on PbS and Cd-doped PbS thin films prepared by chemical bath deposition at different bath temperatures (T-b). The X-ray diffraction (XRD), optical absorption, scanning electron microscopy, and energy dispersive X-ray (EDX) analyses have been performed to explore the properties of PbS and PbCdS films. From the XRD measurements, the particle size (D) of as-deposited PbS and PbCdS films is estimated to be 22 (27) and 12 (9) nm, respectively, for a T-b of 75 (85)degrees C. A reduction in D was noticed upon annealing the films at 200 degrees C, irrespective of the T-b and the doping. The optical band gap energy (E-g) of as-deposited PbS films grown at different T-b is found to be in the range of 1.22-1.42 eV. Doping of PbS with Cd and annealing have led to increase in E-g up to 2.61 (2.66) eV. Optical studies revealed prominent blue shifts in the E-g of as-deposited and annealed films due to quantum confinement effect. The addition of Cd into PbS was confirmed by EDX analysis. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.