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 degreesC) inside a high-temperature cell. The effect of a nucleation pretreatment at 460 degreesC 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. (C) 2001 Elsevier Science B.V. All rights reserved.