Ion beam induced anisotropic deformation of Si nanosprings

Five-armed Si nanospring coatings were grown by glancing angle deposition on Si(1 1 1) substrates pre-patterned with sub-micrometre sized silica and polystyrene spheres. The stiffness of the individual Si nanosprings was determined by atomic force microscope based force–distance spectroscopy. These Si nanospring coatings were irradiated with 1.2 MeV Ar+8 ions at liquid nitrogen temperature at different ion fluences varying from 1015 to 1017 ions cm−2. The pitch of the nanosprings shows a decrease in length and an increase in the width of its arms after the irradiation. The ion beam induced anisotropic deformation of nanosprings was explained in terms of the ion hammering effect. Overall, a 3.5 fold increase in the stiffness of the nanosprings is observed which depends on the ion fluence. The improved mechanical strength of the post-irradiated Si nanosprings coatings indicates that these coatings are capable of withstanding higher loads without getting delaminated.