RBS and ion channelling surface analysis by 8.0 MeV lithium beams

Rutherford Backscattering (RBS) of lithium ions is investigated to study the near-surface region of different targets. Lithium beams, 8 MeV in energy, are produced by the tandem accelerator of the Laboratorio Nazionale del Sud of Catania (Italy). RBS is applied to monocrystalline silicon substrates to perform, in axial and planar ion channelling, ion implantation “in situ” of heavy ion species at high energy (∼0.5 MeV/amu). Arsenic ions, 40 MeV in energy and doses ranging between 1 and 8 × 1015 at/cm2, are implanted in silicon substrates to modify the electrical resistivity of deep layers. This paper presents the limitations of the technique, the mass sensitivity, the cross sections involved and the minimum detection amounts compared to the traditional RBS of helium beams.