Velocity effect on the nanostructure creation at a solid surface by the impact of slow highly charged ions

Energy deposition and formation of nanostructures in the interaction of highly charged xenon ions with gold nanolayers

“…As the results, we obtained the well pronounced modification of the surface in the form of craters. In the present paper, the results are interpreted within the prediction of the micro-staircase model [28,12] and molecular dynamics simulations for single ionized xenon hitting crystalline gold surface [29]. According to the micro-staircase model, simultaneously with the ion cascade neutralization above the surface, the neutralization energy deposits into the solid inducing the first destabilization of the target as a consequence of the high free electron density characteristic for conducting surfaces.…”

“…The neutralization energy of the HCI in the interaction with solid surface is also large for very slow ions (in keV energy range). As a consequence, the interaction of slow single HCI with a surface is also governed by the potential (neutralization) energy of the ion [10,11,12]. This energy is deposited on a small surface area along the first few nanometers below the target surface [13].…”

“…On the other hand, for moderate ionic velocities (v ≈ 0.25 a.u.) both the neutralization and the deposited kinetic energy participate in the surface modification [10,12]. Nanostructures created using HCI can have a form of hillocks, craters (called also pits) or caldera-like structures, with diameter of about 5-20 nm and a few nanometers vertical extension [15,16,11].…”

“…The recent studies of nanostructures formation on surfaces by HCI concentrate mainly on the basic characterization of nanostructures and fundamental understanding of the mechanisms responsible for the surface modifications [15,10,12]. Moreover, most of the experimental observations were performed for insulator while for semiconductors (pure Si) and metals (Ti, Au) only single experiments were carried out, which due to the lack of the systematic studies did not allow for a detailed examination of the mechanism of nanostructures production on such surfaces [16].…”

“…Up to now, the proposed theoretical models of the nanostructure production by slow single HCI, including Coulomb explosion [19,20,21], molecular dynamics simulations [22,23], inelastic thermal spike model [24,25], and plasma model [26,27] describe the mechanism only in a qualitative manner and agree quantitatively only with the results of selected experiments, mainly for insulators. For the metallic surface modifications, the micro-staircase model of the HCI neutralization accompanied by the charge dependent model of the kinetic energy loss has been proposed [28,12].…”