Laser Annealing of Sapphire with Implanted Copper Nanoparticles

Copper nanoparticles have been synthesized by ion implantation in sapphire at 40 keV to a dose of 1x10e17 cm-2, at a current density from 2.5 to 12.5 microA. The samples were treated using pulses of a high-power KrF excimer laser (248 nm) in ambient atmosphere. This employed a single (25 ns) pulse fluence of 0.3 J/cm2 for Cu-implanted sapphires. Number of pulses of the same energy density and at a frequency of 1 Hz were accumulated in the same area on the surface. The formation and modification of metal nanoparticles were assessed via optical reflectance. Generally, changes induced by laser pulses suggest that there are reductions of the size of the nanoparticles without diffusion of metal atoms inward the sapphire. No evidence for oxidization of Cu nanoparticles was founded.