Surface ion implantation induced by laser-generated plasmas

Abstract

Surface ion implantation induced by laser-generated plasmas was investigated using the PALS Prague laser facilities. Cu, Ge, Ag and Ta ions were obtained through the ablation of solid targets in vacuum by means of 10¹⁵ W/cm² laser pulses. Energetic ions (∼ 0.1–1 MeV) were implanted on different substrate surfaces (Si, C, Al, Ti and polyethylene) placed at different distances from the target and angles from the normal to the target surface. In order to increase the ion dose, implantation was performed by using more laser shots in the same experimental conditions. An ion energy analyzer was employed for online measurements of the ion energies and charge states produced by the laser plasma. Off-line Rutherford backscattering spectroscopy (RBS) of alpha particles allowed us to determine the ion depth profiles, the ion energies and the ion amount implanted on the substrate surfaces. RBS spectra have shown typical implanted deep profiles only for substrates placed along the normal to the target surface at which the ion energy is maximum. At large angles, no implantation occurs and ions are only deposited. At a high dose, the multi-energetic ion implantation can be used to modify the physical and chemical properties of the implanted layer surfaces.

Keywords:

• laser ablation
• laser plasma
• ion implantation
• RBS analysis

Acknowledgements

The authors of this paper thank Dr N. Campo and Dr A.M. Visco for the collaboration related to the measurements of the surface roughness and of wettability of the implanted polymers.