Si nanocrystals formation by a new ion implantation device

Metallic and non-metallic ion beams can be used to modify the properties of wafer surfaces if accelerated at a moderate energy. We developed a new “implantation machine” able to generate ions and to accelerate them up to 80 kV. The ion generation is achieved by a laser-plasma source which creates plasma in expansion. The device consists of a KrF excimer laser and a generating vacuum chamber made of stainless steel. The laser energy was 45 mJ/pulse, providing a laser fluence of about 4.5 J/cm2 and a power density of 2.25x108W/cm2 by means a convergent lens. The target support was a stem mounted on an insulating flange and kept to positive voltage to accelerate the produced ions. The ion dose was estimated by a fast Faraday cup polarised at negative voltage. This machine was utilised to try synthesizing silicon nanocrystals in SiO2 matrix. In this work we present the preliminary results of Si ions implanted onto SiO2 films and the glancing-angle X-ray diffraction analyses.