Formation of High Density ⟨111⟩ Textured Nanotwins in Evaporated Ag Thin Films Through Post-Deposition Ion Bombardment

For the production of Ag thin films containing a high density of nanotwins, evaporated Ag films were bombarded with an Ar+ ion beam with voltage of about 0.1 KeV. After the post-evaporation ion bombardment for 15 min, the equiaxial coarse grains in the surface region of the originally as-evaporated Ag films transformed into slender nanotwinned columns containing a highly111textured nanotwinned structure with very thin twin spacing of about 8.6 nm. The nanotwinned columns increased with extension of the ion bombardment time to 30 min. The appearance of (111)-oriented fine grains in top-view electron backscatter diffraction (EBSD) images confirmed the high density of Ag nanotwins. Meanwhile, the roughness of the thin films increased after ion bombardment of the evaporated Ag films. Finally, a mechanism of nanotwin formation based on stress relaxation in evaporated Ag films through post-deposition ion bombardment is proposed.