Nucleation and growth of CdTe1−xSx nanocrystals embedded in a borosilicate glass. Effects of sulfur content and two-step thermal annealing

Nucleation and growth of CdTe1−xSx nanocrystals embedded in a borosilicate glass matrix and submitted to isothermal annealing were studied by small-angle X-ray scattering (SAXS). Two different sulfur contents (x=0.3 and x=0.7) were investigated. The formation and growth of the nanocrystals was studied in situ, maintaining the samples at a constant temperature (560 °C) inside a high-temperature cell. The effect of a nucleation pretreatment at 460 °C on the characteristics of nanocrystal formation and growth was also studied. The experimental results demonstrate that, in composites with high sulfur content (x=0.7), nanocrystals grow during the isothermal annealing by coarsening of preformed small crystals. In glasses with low sulfur content (x=0.3), nanocrystals grow by progressive diffusion of Cd, Te and S atoms initially dispersed in the glass matrix.