CdS x Se1-x quantum dots studied through optical absorption, steady-state photoluminescence, and resonant Raman spectroscopies

Abstract

CdS (x) Se1-x nanoparticles or quantum dots (QDs) were grown in borosilicate glass by a two-step heat-treatment process from a melt-quenched color filter glass. We incorporate the results of optical absorption, steady-state photoluminescence (PL), and resonant Raman spectroscopies in the study of growth kinetics of CdS (x) Se1-x QDs. A modeling of PL spectra employing two Gaussian emission bands and a quantized-state effective mass model in the strong confinement regime reveals that (i) the average particle size ranges from 1.7 to 8.5 nm, (ii) the size dispersion narrows down to 0.22 nm for a single sample, and (iii) QDs form by diffusion-limited growth. We presume that size-dependent higher energy PL band close to the asymptotic absorption edge is due to surface-assisted electron-hole recombination since the difference between optical absorption and PL bands decreases from 239 to 122 meV with increasing average radius.