The effect of low energy irradiation, where the sputtering is imperceptible, has not been deeply studied in the pattern formation. In this work, we want to address this question by analyzing the nanoscale topography formation on Si surface, which is irradiated at room temperature by Ar + ions near the displacement threshold energy, for incidence angles ranging from 0 to 85 •. The transition from smooth to ripple patterned surface, i.e. the stability/instability bifurcation angle is observed at 55 • , whereas the ripples with their wave-vector is parallel to the ion beam projection in the angular window of 60-70 • , and with 90 • rotation with respect to the ion beam projection at the grazing angles of incidence. A similar irradiation setup has been simulated by means of molecular dynamics, which made it possible, firstly, to quantify the effect of the irradiation in terms of erosion and redistribution using sequential irradiation and, secondly, to evaluate the ripple wavelength using the crater function formalism. The ripple formation results can be solely attributed to the mass redistribution based mechanism, as erosion due to ion sputtering near or above the threshold energy is practically negligible.

We report here on a newly installed gas aggregation type nanocluster deposition unit based on magnetron sputtering ion source with mass selection of the clusters by quadrupole mass filter. The system is ultra high vacuum compatible and is equipped with an in situ X-ray Photoelectron Spectroscopy facility, giving compositional information of the films formed by nanoclusters deposition on a substrate. Detailed descriptions and working of the components of the system are presented. For the characterization of the nanocluster source and associated mass filter for size selected clusters, the dependence of output performance as a function of aggregation length, sputter gas flow and magnetron power of the cluster source have been studied. Copper nanoclusters deposited on Silicon (100) surface and on transmission electron microscope grids are, respectively, studied with scanning electron microscopy and transmission electron microscopy for the morphology.

We report the oxidation dynamics of a copper nanocluster assembled film, containing fractal islands, fabricated by the soft-landing of size-selected copper nanoclusters with an average diameter of 3 nm.

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