The Effects of Embedding Medium and Size on Optical Properties od II-VI Core-Shell Nanocrystals

Optical properties of typical II-VI semiconductor coreshell nanostructures are investigated in a wide range of visible and near-infrared spectrum of light. Indeed, absorption, scattering and extinction coefficients are calculated in these nanostructures by using the scattering Mie theory in dipole approximation. To implement the calculations, Mie theory requires the dielectric function to be clearly defined, so in this work an explicit expression of frequency-dielectric function for both the core and shell is used and it includes the phonon and plasmon contributions. The effects of the substitution of the embedding material and the size of nanostructure are investigated on the optical parameters. In fact, the absorption and scattering coefficients are higher for greater size of the nanocrystals. Higher scattering coefficient is obtained when the embedding medium is polyethylene, while higher absorption is observed when the insulating medium is glass. On the other hand, absorption coefficient is 4 to 5 order of magnitude lesser than the scattering coefficient, then the extinction is mainly due to scattering processes. Finally, good agreement between theoretical and experimental results reported in the literature are obtained for extinction coefficient in II-VI core-shell nanostructures.

The Effects of Embedding Medium and Size on Optical Properties od II-VI Core-Shell Nanocrystals Articles