COMPOSITIONAL EFFECT ON THE OPTICAL ABSORPTION AND PHOTOLUMINESCENCE OFCdS_xSe_1-xQUANTUM DOTS EMBEDDED IN BOROSILICATE GLASSES

Abstract

The effect of composition on the optical absorption and photoluminescence (PL) spectra of the semiconductor quantum dots (QDs) of CdSxSe1-xembedded in borosilicate glass matrix has been studied. It is observed that the first exciton absorption peak shifts from 2.62 to 2.21 eV and the PL peak shifts from 2.16 to 1.87 eV as the composition of selenium increases from 8 to 92 wt%. Samples having higher concentration of sulfur are found to have higher PL peak intensity, which is interpreted to be due to high concentration of shallow traps in the sulfur-rich samples. Absorption coefficient goes on increasing as the selenium content increases. This may be attributed to the fact that selenium has higher atomic size as compared to that of sulfur.

The effect of cadmium vacancies on the optical properties of chemically prepared CdS quantum dots

“…It is observed that with an increase in PVA concentration from 5 to 8 wt.%, the absorption edge shifts from 3.1 to 3.6 eV. The blue shift of the absorption edge is due to an increase in quantum confinement of QDs [16,17]. The average radii of QDs are calculated using the following relation given by Barman et al [18]: 3) represents the kinetic energy of the confined exciton and the second term (II) is the Coulomb interaction of the electron with the hole.…”