Optical and structural investigations of antimony-doped cadmium sulphi
de thin films prepared by a modified chemical deposition process are d
escribed. The samples were prepared in an aqueous medium at a depositi
on temperature of 85+/-2 degrees C and a pH of around 8.5. The samples
were doped with various concentrations of Sb3+ in the concentration r
ange 0.005-1 wt.%. Measurements of the absorption coefficient in the e
nergy range 1.6-3.5 eV for both CdS and CdS:Sb crystalline thin films
have been carried out. A careful analysis of the absorption coefficien
ts indicated the crystalline character of the samples studied; a simil
ar diagnosis was obtained from the X-ray and SEM analyses. The absorpt
ion coefficient is of the order of 10(4) cm(-1), and the optical energ
y bandgap decreases with increasing doping concentration, typically fr
om 2.47 to 1.7 eV. The absorption edge shifts towards the higher-wavel
ength side and becomes broader as the doping concentration is increase
d. The samples are polycrystalline, and the crystallinity increases af
ter doping up to a 0.075 wt.% doping level and decreases thereafter. I
n both cases the samples consist of phases of cubic and hexagonal stru
ctures. Additional peaks corresponding to Sb2S3 orthorhombic phases an
d some other small peaks due to excess Cd and S have also been observe
d.