Gisaxs Study Of Cadmium Sulfide Quantum Dots

In order to investigate the structure of semiconductor/glass composites prepared by ion implantation, the grazing incidence small angle X-ray scattering (GISAXS) technique was applied to CdS nanocrystals synthesized inSiO2by implanting separately the constituent Cd and S atoms with a dose of1017/cm2each, which resulted in a Gaussian depth density distribution of the dopants. Subsequently the samples were annealed at 700°C in order to form CdS particles. Due to the high concentration of nanocrystalline CdS, the scattered intensity is not following simple homogenous film models. Instead, additional particle scattering contribution is detected, as well as a multiplicative contribution due to inplane (lateral) particle correlation. From the first one, the particle size is estimated to be 4.6 nm, while an interparticle distance of 15–25 nm is deduced from the latter. Taking into account the applied dose, these values suggest that either part of the Cd and S ions are still dissolved in the amorphous substrate after annealing, and thus are not contributing to the CdS nanoparticle formation, or that implanted atoms have diffused deeper into the substrate during annealing.