We fabricated Mn-doped CdSe QDs by mixing Mn-acetate (Mn(CH$_{3}$CO$_{2}$)4H$_{2}$O) with 0.5 mmol of cadmium oxide (CdO) in the stage of Cd$^{2+}$ precursor synthesis and investigated the effects of Mn doping. When the amount of Mn-acetate mixed was below 0.1 mmol, the properties of QDs doped like PL spectra and the XRD patterns, were not different from those of undoped QDs, and this resulted from the difference in reaction rates for Cd-Mn and Mn-oleate formation. On the other hand, when the amount of Mn-acetate mixed reached 0.5 mmol, the XRD patterns and the PL spectra showed that the doped QDs had a core-shell structure a CdSe core with a big band gap energy and a MnSe shell with small band gap energy, and in this core-shell structure, the surface passivation ligands changed from Cd-oleate of CdSe to Mn-oleate of MnSe.

Keywords: Mn doping, CdSe QDs, CdO, Mn-acetate, FT-IR, EDS, XRD, PL, Raman shift