COMPOSITIONAL EFFECT ON THE OPTICAL ABSORPTION AND PHOTOLUMINESCENCE OF CdSxSe1-x QUANTUM DOTS EMBEDDED IN BOROSILICATE GLASSES

The effect of composition on the optical absorption and photoluminescence (PL) spectra of the semiconductor quantum dots (QDs) of CdSxSe1-x embedded 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.