PREPARATION AND OPTICAL ABSORPTION PROPERTIES OF CDS, ZnS, ZnXCd1-XS AND CORE/SHELL CDS/ZNS NANOPARTICLES

CdS, ZnS, ZnxCd1-xS and CdS/ZnS nanoparticles were synthesized by precipitation of zinc and cadmium cations with sulphide anions in aqueous dispersions of cetyltrimethylammonium bromide (CTAB). UV-VIS absorption spectra of these dispersions were recorded and used for evaluation of the nanoparticles gap energies (E-g). In case of ZnS and CdS nanoparticles the gap energies were used for calculations of their size according to the Brus equation [1]. Size of ZnS and CdS nanoparticles was tuned by the concentration of CTAB. The gap energies of ZnxCd1-xS were found to be linearly dependent on the composition x (varying from 0 to 1) in agreement with to the Vegard law: E-g = 2.57 + 1.40 x. The gap energies of CdS/ZnS systems revealed tunnelling of electrons and holes from the CdS core through the ZnS shell and also indicated relaxation of a strain in the shell with increasing thickness.