Influence of channelling on secondary ion emission yields

Abstract

The sputtering yield of a single crystal changes very sharply with the relative orientation of the primary beam and the lattice. This is related to the channelling effect of the primary ion through the lattice. The secondary ion emission yield varies when a monocrystalline target is rotated around an axis normal to the surface and the incidence angle of the primary beam is kept constant at about 60 degrees. The intensities of different types of ions, monoatomic ions of 0 to 15 eV and fast ions 100 eV, 200 eV, 500 eV, multi-charged and polyatomic species, were recorded as a function of the target orientation. We investigate different ways of reducing the variation of penetrations of the primary ion into the target to suppress the differences of sputtering in order to be able to analyse thin polycrystalline target by making use of the secondary ion emission.