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 moderate energies. 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 with a power density of 2.25 × 108 W/cm2. The target was kept to positive voltage to accelerate the produced ions. The ion dose was estimated by a fast polarised Faraday cup. This machine was utilised to try synthesizing silicon nanocrystals in SiO2 matrix. Preliminary results of Si nanocrystals formation and the glancing-angle X-ray diffraction analyses are reported.