Low-energy ion sputtering has recently attracted increasing interest as an effective method for generation of self-organized nanostructures on the surface of solids with a wide range of possible technological applications. It is well known that under certain conditions, sputtering can produce well-ordered patterns, like ripples or dots on different materials [1-6]. The formation, ordering and size of nanostructures depends on different process conditions. Usually this pattern formation process is considered as a result of the interplay between curvature dependent sputtering that roughness the surface, and different surface relaxation mechanisms that act to smooth the surface.In this contribution the dot and ripple surface topography emerging on Si, Ge and compound semiconductor surfaces during low-energy (≤ 2000 eV) noble gas ion beam erosion at oblique ion incidence is studied. The results show that there is a much more complex behavior of the surface topography with ion energy, ion fluence, angle of incidence, etc.For example, the experimental results show that at certain ion sputtering conditions, at oblique ion incidence ripple patterns can form on Si and Ge surfaces with size below 100 nm. By varying the ion incidence angle a morphological transition from ripple to dot patterns could be observed. Due to self-organization processes and also influenced by the previous existence of ripples, the dot patterns show a long range ordering that covers the whole sample area. For Ge the dots show a hexagonal ordering while for Si the dots show a quadratic ordering. Experimental results reveal that the wavelength of ripples remains constant with increasing ion fluence, while the ordering increases, leading to ripple patterns with a very high degree of ordering. Moreover, the influence of different ion species on pattern formation is investigated. Atomic force microscopy and high-resolution transmission electron microscopy are used to characterize the evolving nanostructures.[1] S. Facsko, T. Dekorsy, C. Koerdt, C. Trappe, H. Kurz, A. Vogt, and H. L. Hartnagel, Science 285, 1551 (1999).[2] F. Frost, A. Schindler, and F. Bigl, Phys. Rev. Lett. 85, 4116 (2000).[3] R. Gago, L. Vazquez, R. Cuerno, M. Varela, C. Ballesteros, and J. M. Albella, Appl. Phys. Lett. 78, 3316 (2001).[4] B. Ziberi, F. Frost, B. Rauschenbach, and T. Hoche, Appl. Phys. Lett. 87 (2005).[5] B. Ziberi, F. Frost, Th. Hoche, and B. Rauschenbach, Phys. Rev. B 72, 235310 (2005).[6] B. Ziberi, F. Frost, and B. Rauschenbach, Appl. Phys. Lett. 88 (2006).

Pattern formation on the surface of different materials due to low-energy ion beam erosion is a versatile tool for large scale nanostructuring. The evolving patterns are arranged in domains of well ordered nanostructures showing hexagonal ordering. However, usually this self-organization process lacks long-range order due to the formation of domains and defects in the pattern. Also there is a little positional control of the evolving structures. One possibility to influence the ordering of structures is by using p