FABRICATION, STUDY OF STRUCTURAL AND OPTICAL PROPERTIES OF UNDOPED AND NI-DOPED CDS NANOCRYSTALS

Abstract

Undoped and Ni-doped CdS (CdS:Ni, with concentrations of 1, 5, 10 and 20%) nanocrystals (NCs) have been prepared by wet chemical method in ODE solvent. The results of TEM imaging show that undoped and Ni-doped CdS NCs have a spherical shape, about 6 nm in size and almost unchanged when changing doped concentrations of Ni. The XRD results indicated that all undoped and Ni-doped CdS NCs crystallize in the cubic phase with zinc-blende structure. The energy dispersive X-ray analysis (EDX) has demonstrated the presence of the Cd, S and Ni elements in CdS:Ni NCs. Raman spectra shows that 1LO and 2LO peaks of the Ni-doped CdS NCs are slightly red shifted when compared to that of undoped CdS NCs. The peaks of fluorescence spectra of CdS and CdS:Ni (1-20%) NCs change in the range of 474 - 483 nm. The absorption peaks of Ni-doped CdS NCs are found to shift towards the lower energy (red shift) when compared to that of undoped CdS and the bandgap is observed to lie in the range of 2.62 -2.72 eV. This result proves that Ni²⁺ ion has entered into the crystal lattice of CdS.