Effect of deformation nanostructuring of nickel and copper on ion sputtering with a focused gallium ion beam with an energy of 30 keV
Ion sputtering of nanostructured, with an average grain size of about 200 nm, fine-grained, with an average grain size of 5 μm, and coarse-grained nickel and copper samples with a focused gallium ion beam with an energy of 30 keV has been investigated. As a result of ion sputtering with a focused ion beam, sputtered (etched) areas with different reliefs have been formed on the surface of the samples. It is shown that the relief formed on the surface of the sputtered area in the process of ion sputtering depends on the grain size of the sample. With a grain size corresponding to the fine-grained or coarse-grained states, sputtering occurs unevenly. With a grain size corresponding to the nanostructured state, sputtering occurs relatively evenly. For the energy of gallium ions 30 keV, the dependence of the maximum relief height Rmax of the sputtered surface on the grain size d of the metal in the range from nanostructured to fine-grained states is established: Rmax≈0.1d. The sputtering yields of nickel and copper samples with different grain sizes are determined. The value of the sputtering yields has been estimated from the measurements of profilograms of the sputtered areas using scanning probe microscopy. It has been established that the deformation nanostructuring of a metal leads to a decrease in the emission of atoms from its surface when bombarded with gallium ions with an energy of 30 keV. Thus, the sputtering yield of coarse-grained nickel and copper is 4.8±1.5 and 4.9±1.3 atom/ion, respectively, of fine-grained nickel - 4.1±1.6 atom/ion, nanostructured nickel and copper - 2.0±0.5 and 2.1±0.2 atom/ion, respectively. On the basis of the sputtering mechanism in the linear cascade regime, an analysis of the reasons for the decrease in the sputtering yield of the metal as a result of its deformation nanostructuring is made.