AFM study of the effect of direct negative Ni ion beam energy on the evolution of Ni nanoislands

The influence of secondary negative Ni ion beam energy on the evolution of crystalline grains as a function of ion beam energy was investigated. Prior to deposition, we also characterized the property of direct Ni− ion beam source such as secondary Ni− ion yield, ion energy spread, and deposition rate and then by atomic force microscopy analyses we have characterized the morphology and roughness of the ion beam bombarded surface. Increasing the ion beam energy resulted in an increase in the surface roughness which can be explained by the growth of separated cone shaped grains. However, beyond 75 eV roughness decreased by the reduction of grain size due to many nucleation sites. Thin film deposition rate also decreased as increasing ion beam energy