Ion Bombardment-Induced Surface Effects in Materials

Abstract

This chapter deals with the experimental research and computer simulation of low-and medium-energy (E 0 = 1-30 keV) ion collisions on the surface of a solid and of the accompanying effects, namely scattering, sputtering, and surface implantation. Experimental and computer simulation studies of low-energy (Е 0 = 80-500 eV) Cs + ions scattering on Ta, W, Re target surfaces and K + ions scattering on Ti, V, Cr target surfaces have been performed for more accurate definition of mechanism of scattering, with a purpose of evaluation of use of slow ions scattering as a tool for surface layer analysis. The peculiarities of the process of correlated small angle scattering of 5-15 keV He, Ne, Ar, Kr, Xe, and Rn ions by the Cu(100), Ni(100), and V(100) single-crystal surfaces have been investigated by computer simulation. It has been shown that under these conditions the inelastic energy losses become predominant over the elastic ones. The anomalous energy losses observed experimentally at the grazing ion scattering by the single-crystal surface were explained. It has been shown by computer simulation that the peculiarities of the chain effect at direct and reverse relation of masses of colliding particles and rainbow effect at quasi-single and quasi-double scattering of ions, heavier than adatoms, lead to the appearance of characteristic peaks in the energy and angular distributions of scattered ions. Analysis of these peaks and comparison with experiment give an opportunity to control the initial stages of adsorption and identification of adsorption structures with the help of low-energy ion scattering. It has been shown that from the correlation of the experimental and calculated energy distributions of the scattered particles, one may determine a spatial extension of the isolated atomic steps on the single-crystal surface damaged by the ion bombardment. Results obtained can be also used to study short-range order in alloys undergoing ordering. Grazing ionsputtering processes of Si(001), SiC(001), and Cu 3 Au(001) surfaces at 0.5-5 keV Ne + bombardment have been studied by computer simulations. A preferential emission of Cu atoms in the case of Cu 3 Au (001) surface sputtering is observed. It was shown that in the case of grazing ion bombardment, the layer-by-layer sputtering is possible, and its optimum is observed within the small angle range of the glancing angles near the threshold sputtering angle. The peculiarities of trajectories, ranges, and energy losses of low-energy different-mass ions channeling in thin single crystals of metals and semiconductors have been thoroughly studied by computer simulation. It has been ion bombardment, elastic and inelastic energy losses, vacancy and atomic steps defects on the surface, method of layer-by-layer analysis of single-crystal surface,

Guided Vortex Motion Control in Superconducting Thin Films by Sawtooth Ion Surface Modification

“…The lack of a zero resistance state is likely due to backscattering and ion implantation damaging YBCO structure from the angled ion beam. 28 If we assume elastic scattering, then the backscattering length estimate is the thickness of the scattering wall (photoresist + YBCO film thickness) × tan (ion beam incidence angle), that is, (1.5 μm) × tan(75°) = 5.6 μm. Because the scattering "wall" is not perpendicular to the substrate (SR in Figure 1a), the backscattering length would be even larger.…”