Surface modifications of BaF2 and CaF2 single crystals by slow highly charged ions

Abstract

Ion-irradiation of solid surfaces is considered as one of the promising and powerful techniques for material nanostructuring. Recently, slow highly charged ions (HCI) have shown their potential in creating surface nanostructures in various solids. Here, we focus on the surface modifications of BaF 2 and CaF 2 single crystals by HCI. Despite the fact that both materials belong to alkaline-earth fluorides with the same crystalline structure, they exhibit different sensitivity for HCI-induced nanostructure. We discuss similarities and differences for the creation of HCI-induced nanohillocks and etch pits in both materials and their dependence on potential and kinetic energy deposition. Furthermore, we compare the results with modifications induced by swift heavy ions (SHI), in order to reach a better understanding of the mechanisms responsible for the creation of nanostructures in ionic fluoride single crystals.

Response of GaN to energetic ion irradiation: conditions for ion track formation

“…From Fig. 7 one can see that recently obtained experimental data points for LiNbO3 [65], BaF2 [66] and Al2O3 [67], together with the present new data for GaN, exhibit a large scatter. This is different from an earlier study where a more uniform threshold behavior for a variety of other materials was found [22].…”

“…As can be seen from Fig.7, especially more experimental work on HCI irradiation of TiO2 crystalline materials from ref. [22] updated with data for LiNbO3 [65], BaF2 [66], Al2O3 [67] and GaN (present work, in red). According to the ATSM, the formation of HCI tracks should be forbidden in the area marked in red.…”

Highly charged ion induced nanostructures at surfaces by strong electronic excitations

“…(b) AFM image of etch pits on BaF 2 surface by impact of highly charged Xe 19+ ions (E kin = 85 keV) through a structural mask after chemically etching using HNO 3[79], figure taken from[82]. (c) c-AFM image of hillock structures on CaF 2 (111) surface by impact of highly charged Xe 33+ ions (E kin = 66 keV)[5], figure taken from[76].…”

Charge‐State‐Enhanced Ion Sputtering of Metallic Gold Nanoislands

“…[7] Naturally, this makes insulators and semi-conductors more prone to modifications by slow highly charged ions (HCI). [8][9][10][11][12] Metallic surfaces have not unambiguously shown a susceptibility to potential energy deposition as high as 40 keV per incoming ion, [13,14] even in the case of freestanding two-dimensional graphene. [15] It is assumed that the intrinsically high charge carrier mobility in metals dissipates electronic excitations before a coupled atomic motion can set in.…”