Structural, optical, FTIR and photoluminescence studies of CdS_1−xSe_x thin films by chemical bath deposition method

The ternary CdS_1−xSe_x alloy thin films with the nominal composition of x = 0.2, 0.4, 0.6 and 0.8 have been synthesized on glass substrate by chemical bath deposition (CBD) method at 80°C from aqueous solution. Crystalline phases and optical absorption of the films have been studied by X-ray diffraction and UV–visible spectrophotometer. Elemental composition of the CdS_1−xSe_x films was studied by the energy dispersive X-ray (EDX) analysis. The optical absorption and transmission studies revealed that CdS_1−xSe_x films had direct allowed transition with band gap energy decreased from 2.28 to 1.92 eV as thickness varied from 762.4 to 621.2 nm. The average crystalline size was calculated from X-ray line broadening and it is increased from 12.71 to 14.67 nm for x = 0.2–0.8 which was confirmed by SEM studies. The substitution of Se concentrations into the Cd–S and Cd–S–Se lattice is confirmed by the increase of lattice parameters, FTIR and photoluminescence studies. The broad variation in the band gap of CdS_1−xSe_x thin films have potential applications in the field of optoelectronic devices.