Effect of Grain Size and Texture of Polycrystalline Tungsten on Its Ion-Beam Sputtering

The effect of grain size and texture of polycrystalline tungsten on the sputtering yield and surface morphology under high-fluence irradiation with 30 keV Ar⁺ ions has been studied. Samples with the average grain size from 300 nm to 7 μm without texture and with a [001] texture have been used in the experiment. It is shown that the ion-induced surface morphology strongly depends on the grain size and irradiation fluence. The grain size has little (less than 10%) effect on the sputtering yield, while the texture can reduce the sputtering yield by a factor of two. An experiment with varying angle of incidence of the ion beam has shown that the channeling effect is the reason for the twofold decrease in the sputtering yield for textured samples. The influence of the surface relief on the sputtering yield has been analyzed. An expression taking into account atomic redeposition and ion reflection is proposed to predict the sputtering yield of a surface with ion-induced relief.