Composition Dependent Structural and Optical Properties of Nanocrystallites ZnxCd1-xS

In this work a novel chemical reduction method at room temperature is described to synthesize nanocrystalline ZnS, CdS, ZnxCd1-xS. The method is cheap and cost effective. The grown nanoparticles are characterized by XRD, TEM, EDX, UV-VIS absorption and PL study. CdS formation is supported by the systematic splitting of x-ray diffraction peak at lower angle and the peaks are identified. ZnS peaks are also identified comparing with ICDD data. EDX analysis shows two other phases Zn 0.8 Cd 0.2 S, Zn 0.5 Cd 0.5 S. The particle sizes are in the range 4-8 nm. The band gap changes with change of composition. Also at each composition the band gap is greater compared to bulk band gap. This indicates quantum confinement takes place. The band gap energy of nanoparticles can be tuned to a lower energy by increasing the Cd content, indicating the formation of the alloyed nanoparticles. PL peak shifts towards higher wavelength as Cd content increases. The peak corresponds to transition associated with surface state.