Synthesis of Cd1-xMnxS quantum dots via reverse micelles and its photoluminescence performance

Incorporation of diluted magnetic semiconductors (DMS) in quantum confined systems opens pew possibilities for the spin-dependent electronics due to the combination of the exchange interaction and the quantum confinement. In this work, we focus on the synthesis and optical properties of Cd1-xMnxS. quantum dots (QDs). Cd1-xMnxS quantum dots (QDs) were prepared via a reverse micelles. The size of dots was controlled by changing the ratio of w(o)(w(o)=[H2O]/[AOT]). A series of Cd1-xMnxS QDs samples with w(o) varying from 3.5 to 5.5 were prepared. A high-resolution electron transmission microscopy (HRTEM) study of QDs with w(o)=3.5 shows that the QDs are nearly mono-dispersed with an average diameter around 4.8 nm and the QDs are defects-free single crystals. The Cd1-xMnxS QDs size is varying from 4.8, 5.1, 5.3 to 6.0 nm with w(o) varying from 3.5, 4.5, 5.0 to 5.5. The molar fraction of Mn2+ in the Cd1-xMnxS dots is About 1.5% with respect to (Mn2++Cd2+) determined by X-ray energy dispersion spectroscopy. Electron spin resonance spectroscopy shows that Mn2+ ions are in tetrahedral sites indicating that Mn2+ are incorporated into the US lattice. The absorption spectra of these samples exhibit a well-defined excitonic peak located from 2.88 eV to 3.28 eV corresponding to the different values of w(o). The longer wavelength of the absorption peak is exhibited with the larger w(o). Most interestingly, the pho-, toluminescence emission peaks are red-shifted from 2.26 eV to 1.88 eV with increasing the w(o) values from 3.5 to 5.5. These emission peaks are believed to originate from the Mn2+ T-4(1)-(6)A(1) transitions in associated. states.