FE-SEM observation of chains of nanohillocks in SrTiO3 and Nb-doped SrTiO3 surfaces irradiated with swift heavy ions

Nanopatterning surfaces by grazing incidence swift heavy ion irradiation

“…These surface tracks are typically a few hundred nanometers in length and a few nanometers high. The typical nanohillock diameters of tens of nanometer, as well as the nanohillocks spacings, are also well in agreement with previously reported values [21][22][23]61]. The exposure of the SrTiO3 surface to a higher fluence irradiation results in overlapping ion tracks also shown in Fig.…”

“…Further work should be done in this regard, probably by choosing another material like a-SiO2 where ion tracks would be continuous. Finally, observing directly a single etched ion track on the surface by means of HRTEM, offers another piece of information about the surface ion track formation process [61,76]. Most importantly, it seems the material that contributes to forming the nanohillock on the material surface, does not originate from large depth, at least in the case of grazing SHI irradiations [77].…”

Mechanisms of surface nanostructuring of Al2O3 and MgO by grazing incidence irradiation with swift heavy ions

“…Grazing incidence SHI irradiation makes identification of the SHI impact sites much easier, allowing studies of unusual track morphologies and processes occurring during the SHI-surface interaction [7,[40][41][42][43][44][45]. For example, an origin of chainlike morphology of surface ion tracks has been attributed to the oscillating stopping power when SHI encounters different electronic densities when passing through the crystal layers at grazing incidence angles [40].…”

Surface nanostructures on Nb-doped SrTiO3 irradiated with swift heavy ions at grazing incidence

“…In case ceramics are irradiated with SHIs at normal incidence, a single hillock is formed at the incident surface by each ion impact. In contrast, when ceramics are irradiated with SHIs at grazing incidence, multiple hillocks in a chain can be created along the ion trajectory [13][14][15][16][17][18][19][20][21][22]. Formation of hillock chains was first reported on SrTiO 3 (STO) [13], and later it has been reported also on several other ceramics, such as TiO 2 [18,19], SiO 2 [20,21] and STO doped with niobium [22].…”

“…In contrast, when ceramics are irradiated with SHIs at grazing incidence, multiple hillocks in a chain can be created along the ion trajectory [13][14][15][16][17][18][19][20][21][22]. Formation of hillock chains was first reported on SrTiO 3 (STO) [13], and later it has been reported also on several other ceramics, such as TiO 2 [18,19], SiO 2 [20,21] and STO doped with niobium [22]. Since the intermittent feature of hillock chains created at the surface is in contrast to continuous feature of ion tracks created in the bulk, it is not straightforward to relate the mechanism of hillock chain formation to that of ion track formation in the bulk.…”