Nucleation and growth of CdTe1-xSx nanocrystals embedded in a borosilicateglass. 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-an gle 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 s tudied in situ, maintaining the samples at a constant temperature (560 degr eesC) inside a high-temperature cell. The effect of a nucleation pretreatme nt at 460 degreesC on the characteristics of nanocrystal formation and grow th was also studied. The experimental results demonstrate that, in composit es with high sulfur content (x = 0.7), nanocrystals grow during the isother mal annealing by coarsening of preformed small crystals. In glasses with lo w sulfur content (x = 0.3), nanocrystals grow by progressive diffusion of C d, Te and S atoms initially dispersed in the glass matrix. (C) 2001 Elsevie r Science B.V. All rights reserved.