Structural and optical properties of silica capped ZnS:Mn quantum dots

Abstract

In the present work, the structural and optical properties of Silica capped ZnS:Mn quantum dots (QDs) has been reported. Chemical precipitation technique was used to form the core-shell nanostructures. The results indicate that the Silica capped ZnS:Mn QDs has cubic Zinc Blende structure and its grain size is about 2 nm as demonstrated by X-ray diffraction (XRD). Transmission electron microscopy images showed that the presence of Silica capping on ZnS:Mn QDs can prevent their agglomeration by cluster formation and their particle size (2-3 nm) well matches with XRD results. The selected area diffraction pattern shows a set of sharp rings corresponding to the (111), (220) and (311) lattice planes of the cubic phase of ZnS which proves the polycrystalline behaviour. Band gap studies were done by UV-visible spectroscopy and presence of Silica have been confirmed by EDAX and FTIR analysis. Photoluminescence studies shows emission wavelength as well as intensity to be tunable with Silica capping. As Silica capped ZnS:Mn QDs can control various parameters of ZnS:Mn, they are suitable material for specific kind of tunable optoelectronic devices.