The effect of Cd substitution in PbS thin film on the optical properties

Thin films of cdxpb1-x s were prepared by chemical spray pyrolysis with ( x=0.6 , 0.7 , 0.8 , 0.9 , 1 ) .the optical properties of prepared thin films were studied by uv-vis spectrophotomer . from the measurement of absorption and transmission , the optical parameters and the optical energy gap (eg) were calculated .the optical energy gap (eg) was increased with increasing the value of cd from 1.2 ev when x=0.6 to 2.4 ev when x=1 . the maximum value of refractive index (n) is equal to 2.5 and the maximum value of extinction coefficient is varied between 0.2 to 0.45 depending on the value of x . the film with x=0.7 was doped by ag in the ratio 1% ,3% and 5% . the film after dopping have a direct energy gap also and the value of eg were increased with increasing (ag) ratio , these values increased from 1.2 ev for absent ag to 1.74 ev for 5% ag .