THE EFFECT OF DOPING BY CD AND PB ON THE OPTICAL PROPERTIES OF THIN FILM (CU0.5AG0.5ALS2 )

Abstract

:Cu0.5Ag0.5AlS2 thin film had been doped by (Cd) and (Pb) elements, with amount of (1, 2, 3, 4, 5)wt% and studied the effect of doping by Cd and Pb on the optical properties for this thin film which prepared by chemical spray pyrolysis at 360Co .When the thin film was doped by Cd ,from the absorption and transmission spectrum of the prepared thin films in the range (300 – 1000) nm, the optical constants were calculated. The absorption coefficient (α) was found greater than( 104)cm-1 for all films , this means that the electronic transitions of allowed direct type and the absorption edge was shifted toward the greater wavelength from (506.12)nm for the non-doped film and arrive to (551.11)nm at 5%wtCd and no change of the electronic transitions type . The values of energy gap were decreased from (2.45)eV for the non-doped film to (2.25)eV for the doped film at 5wt%(Cd) . Also the values of (K) were shifted toward the greater wavelengths with increases the doping ratio, the higher values of refractive index (n) were shifted toward the larger wavelength with increases in doping ratio. Also The values of (€1) and (€2) are behave in the shape with increases in doping ratio . When the thin film doped by (Pb) the energy gap values doesn't change and also the other constant for all doping ratios.