Structural and optical characterisation of CdSe_1-yS_y

In this work presents the structural and optical characterisation of cadmium selenide sulphur (CdSe_1-yS_y) deposited by chemical bath deposition (CBD) technique at a deposited temperature of 20±2 °C varying the sulphur molar fraction from 0% to 42.13%, which is realized by varying the thiourea volume added to the growth solution in the range from 0 to 30 ml. The CdSe_1-yS_y chemical stoichiometry was determined by energy-dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) analysis and Raman spectroscopy reveal that CdSe_1-yS_y deposited nanofilms showed hexagonal wurtzite crystalline phase. The average grain size range of the films was from 1.48-9.2 nm that was determined using the Scherrer-Debye equation from W(200) crystalline direction, which was confirmed by high resolution transmission electron microscopy (HRTEM). CdSe_1-yS_y band gap energy can be varied from 1.86 to 2.15 eV by varying the sulphur molar fraction incorporated in the nanofilms. The room temperature photoluminescence presents a dominant band about 3.0 eV that may be associated with the grain size of the nanoparticles.