Nanoripple formation onTiO2(110)by low-energy grazing incidence ion sputtering

Abstract

The self-formation of metastable nanoripples by low-energy Ar + ions impacting at a grazing incidence angle on a TiO 2 ͑110͒ surface has been investigated by scanning tunneling microscopy. Ripple formation is a consequence of preferential sputtering of monatomic step edges with a directional component perpendicular to the ion-beam azimuth. The combination of preferential erosion of step edges and ion-beam-induced surface roughening results in a surface morphology with nanoripples aligned parallel to the ion-beam azimuth. We investigate the surface-structure evolution as a function of ion fluence for two ion-beam azimuth directions. Analysis of the formation and evolution of sputter-induced vacancy islands shows that under the conditions employed here ͑0.8 keV Ar ions, 8°grazing incidence angle͒ the sputter probability at step edges is significantly enhanced compared to sputtering at flat terraces. Although the initial vacancy island morphology can be strongly influenced by the step-edge formation energies for different crystallographic orientations, both investigated azimuth directions form similar ripple structures at high ion fluences. This study demonstrates that grazing incidence ion beams can be employed to pattern oxide substrates with quasiperiodic nanoripples with ripple spacing of tens of nanometer.

Growth of nanocolumnar thin films on patterned substrates at oblique angles

“…In this paper we aim at developing such framework by studying how substrate features may affect the film nanostructure when using the MS‐OAD technique. In particular, we focus on the effect of one dimensional quasi‐periodic patterned substrates, characterized by peak‐to‐peak distances in the order of few hundred nanometers, very similar to those experimentally obtained by ion beam sputtering . To address this problem, we have first used a well‐accepted model to theoretically simulate and analyze the growth of a thin film on purely periodic and near periodic patterned substrates at oblique angles and, subsequently, experimentally test these results by analyzing the growth of porous SiO 2 thin films on quasi‐periodic ion‐induced patterned Si substrates.…”

Self-organized nanopatterning of silicon surfaces by ion beam sputtering

“…Thus, the advance in the understanding of IBS nanopatterning of Si surfaces can indeed improve the control of this process not only in this material but also in many others, which surely will contribute to develop new and interesting applications for this kind of patterns at the nanoscale. Finally, it should be noted that although this review is focused on nanopatterning of silicon surfaces, recent efforts have been devoted to exploring new applications of IBS nanopatterns by extending the process to other highly functional semiconductors such as TiO 2 [293,294], ZnO [295] or CdTe [296].…”

Teflon impregnated anatase TiO 2 nanoparticles irradiated by 80 keV Xe + ions

“…The combination of the preferential erosion of the step edges and crystallographic oriented enhanced surface diffusion leads to the formation of the nanoripple structures [13]. In another work, it was predicted that the wavelength of nanoripples on Si substrate as a result of Ar + ion irradiation increases with the increasing fluence irrespective of the beam direction thereby indicating presence of dominant ion beam induced diffusion mechanism [39].…”

“…In case of fast ($MeV scale) moving ions, the collision process mainly involves electronic excitations and ionization of atoms, but keV scale ions are relatively slow and encounter direct collisions with the whole atomic nuclei [11]. In the past, numerous works have been carried out with keV irradiation in which nuclear energy loss (which dominates over electronic energy loss) was viewed as the key to alter material properties [9,12,13]. Kitazawa et al have extensively studied photon emission using 10 keV O + ion irradiation [14].…”