Ion beam synthesis of buried CdSe nanocrystallites in SiO2 on (100)-silicon

Nanocrystalline precipitates of the direct band gap II–VI compound semiconductor CdSe were synthesized by sequential high dose ion implantation into thermally grown SiO2 on (100)-silicon. The implantation doses were chosen to be 4×1016 and 8×1016 cm−2, respectively. Rapid thermal annealing of the as-implanted samples at temperatures of 800 and 1100 °C led to the formation of nanocrystalline randomly oriented precipitates of CdSe buried in an amorphous matrix of SiO2. The concentration profile of the implanted elements and the size distribution of the finally formed crystallites were analysed by thin film X-ray diffraction (XRD) and Rutherford backscattering spectroscopy (RBS). High-resolution transmission electron microscopy (HTEM) cross-section images show that the nanocrystallites are defect-free. Moreover, transmission electron microscopy (TEM) images provide direct information on the spatial size distribution of the nanocrystals.