5 research outputs found
Effects of deposition time and post-deposition annealing on the physical and chemical properties of electrodeposited CdS thin films for solar cell application
CdS thin films were cathodically electrodeposited by means of a two-electrode deposition system
for different durations. The films were characterised for their structural, optical, morphological
and compositional properties using x-ray diffraction (XRD), spectrophotometry, scanning
electron microscopy (SEM) and energy dispersive x-ray (EDX) respectively. The results obtained
show that the physical and chemical properties of these films are significantly influenced by the
deposition time and post-deposition annealing. This influence manifests more in the as-deposited
materials than in the annealed ones. XRD results show that the crystallite sizes of the different
films are in the range (9.4 – 65.8) nm and (16.4 – 66.0) nm in the as-deposited and annealed
forms respectively. Optical measurements show that the absorption coefficients are in the range
(2.7×104 – 6.7×104) cm-1 and (4.3×104 – 7.2×104) cm-1 respectively for as-deposited and annealed
films. The refractive index is in the range (2.40 – 2.60) for as-deposited films and come to the
value of 2.37 after annealing. The extinction coefficient varies in the range (0.1 – 0.3) in asdeposited
films and becomes 0.1 in annealed films. The estimated energy bandgap of the films is
in the range (2.48 – 2.50) eV for as-deposited films and becomes 2.42 eV for all annealed films.
EDX results show that all the films are S-rich in chemical composition with fairly uniform Cd/S
ratio after annealing. The results show that annealing improves the qualities of the films and
deposition time can be used to control the film thickness.
Keywords: Electrodeposition; two-electrode system; CdS; annealing; deposition time; thin-film