Influence of ion channeling on backscattering and sputtering yields of niobium single crystals

The secondary ion yields from Nb(100) and Nb(111) crystals bombarded with 3-7 keV Ar ions at various azimuthal and polar angles of incidence are measured. The reductions of the sputtering yields due to channeling along the major planar and axial channels of the crystals are separated. The effect is found to depend on the channel orientation relative to the bombarded surface. The ion penetration is also simulated by using a MARLOWE based computer code. Although the calculated primary ion range is larger at channeling conditions, no substantial enhancement of the focusing effect or the depths of origin of sputtered particles is observed