Defect production by MeV cluster impacts

Behavior of crystalline silicon under huge electronic excitations: A transient thermal spike description

“…Compared to [66,67] our initial energy distribution differs by less than 10% for an Al beam in silicon with energies ranging between 0.37 and 370 MeV/u. The nuclear stopping power was neglected on the basis of the experimental results given by Döbeli et al [32]. Below the threshold of electronic damage creation by C n cluster in Si, the damage induced by nuclear collisions decreases when increasing the electronic energy loss.…”

“…Finally, for silicon irradiated at 300 K by C n carbon clusters at constant velocities (0.8 MeV per carbon with n = 1 -8, leading to S e from 1 to 8 keV/nm), damage production at the surface has been observed [32]. The defects appear for S e larger than 5 keV/nm, and their number increases with S e .…”

“…With the melting criterion and taking into account these values of D e and g, the molten phase arises at an electronic stopping power threshold, S m eth (cluster) = 3.5 keV/nm (Fig. 1, R m at an energy of 0.07 MeV/u) not far from the experimental result (5 keV/nm) [32].…”

“…Moreover, R m = R(E at > E atm ) and R v = R(E at > E atv ) correspond respectively to the sizes of the cylinder in which the molten or the boiling phases appear along the ion path. The calculated track radii and the corresponding electronic energy loss threshold are fitted to the experimental data obtained after fullerene irradiation of silicon [28,29,32]. This procedure allows us to determine the g and D e values for silicon.…”

Metallic cluster beams from a 2.5 MV Van de Graaff accelerator for cluster–solid interaction studies: preliminary results with Aun+ clusters

“…In addition, the Φ c value drops down to ≈ 5 × 10 13 at/cm 2 when the irradiation is performed with clusters. Such a nonlinear effect for defect creation in Si has already been pointed out by means of Ge + n (n ≤ 3) irradiations at an energy of 2.8 MeV per atom [14] and by fullerene irradiations at energies up to 530 keV [15]. Interestingly, the ion emission yields of CsI targets [16] and the sputtering yields of gold targets [17] bombarded with gold clusters exhibit also a nonlinear dependence on the cluster size.…”