Si nanopillar deformation by heavy polyatomic ion impacts

Si nanopillars for the fabrication of vertical nanowire gate-all-around Single Electron Transistors [1], have been irradiated with Si++, Pb+, Pb++, Au +, Au++, Au2 +, and Au3 + ions accelerated by 30 kV. A FIB of mass separated ions, extracted from a Liquid Metal Alloy Ion Source [2], has been scanned over regular arrays of Si nanopillars of different diameters and pillar distances. The irradiations have been performed at RT and 400∘C. Different morphological changes of the pillars like thinning, height reduction, tilting etc. have been observed which can be attributed to ion erosion (sputtering), impact-induced viscous flow or even transient nanosecond-scale melting [3]. The pillars were imaged by AFM, SEM, TEM and HIM. 3D Monte Carlo simulations [4] of ion and recoil trajectories based on the Binary Collision Approximation and Molecular Dynamics calculations have been carried out in order to discriminate the dominating processes. [1] EU project Ions4SET, Horizon 2020 grant No. 688072 [2] L.Bischoff, et al., Appl. Phys. Rev. 3 (2016) 021101 [3] C. Anders, K.-H. Heinig, H. Urbassek, Phys. Rev. B87 (2013) 245434 [4] W. Möller,NIM B322 (2014) 23