Novel approach to the fabrication of Au/Silica core-shell nanostructures based on nanosecond laser irradiations of thin Au films on Si

We demonstrate the possibility to produce Au/SiO2 core/shell nanoparticles by nanosecond laser irradiations of thin (5 and 20 nm) Au films on Si. The Au/Si eutectic reaction and dewetting process induced by the fast melting and solidification dynamics induced by the nanosecond laser irradiations are investigated as origins of the core/shell nanoparticles formation. Crossing several microscopic techniques (Rutherford backscattering spectrometry, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and energy filtered-transmission electron microscopy) the formation and evolution of the core/shell structures are investigated as a function of the laser fluence in the 500-1500 mJ/cm2 range for both the film thicknesses. In particular, the mean height and diameter, and surface density evolutions of the core/shell structures are quantified and correlated to the laser fluence and Au film thickness.