IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Tuesday Sessions
       Session SC+SS-TuA

Paper SC+SS-TuA9
Surface Nanostructuring by Ion Sputtering: The Early Stages

Tuesday, October 30, 2001, 4:40 pm, Room 122

Session: Semiconductor Nanostructures and Processing
Presenter: F. Buatier de Mongeot, Universita' di Genova, Italy
Authors: F. Buatier de Mongeot, Universita' di Genova, Italy
D. De Sanctis, Universita' di Genova, Italy
C. Boragno, Universita' di Genova, Italy
U. Valbusa, Universita' di Genova, Italy
Correspondent: Click to Email
Ion sputtering is commonly used in surface science as a standard sample cleaning procedure. Recently, we have demonstrated that prolonged exposure to an ion beam can lead to the formation of regular patterns on surfaces, which have a spatial periodicity in the nanometer range.@footnote 1@ However, it is not trivial to understand how a random process, like the impingement of ions on the surface, can lead to a regular spatial organization.@footnote 2@ In order to investigate this aspect, we studied the early stages of the process by a Variable Temperature Scanning Tunneling Microscope VT-STM. The ion flux was reduced in order to follow the time evolution of the surface self-organization, starting from the single-impact events and until the formation of ripples on an Ag(110) surface occurred. We fixed the ion impact angle to 70 deg from the normal and low substrate temperatures, in order to enhance the erosive contribution.@footnote 1@ Under these experimental conditions, prolonged exposure to the ion beam leads to the formation of a regular ripple pattern parallel to the ion beam direction with a wavelength in the nm range. Surprisingly, in the early stages, after exposing the surface to an ion dose as low as 0.03 ML the surface morphology shows a well defined correlation along the crystallographic directions and only at higher fluences the correlation figure alignes with the ion beam. In this contribution we discuss the relevant parameters of this phenomenon. @FootnoteText@ @footnote 1@ S.Rusponi, G.Costantini, F.Buatier de Mongeot, C.Boragno and U.Valbusa, Appl.Phys.Lett. , 75 (1999) 3318 @footnote 2@ G. Costantini, F. Buatier de Mongeot, C. Boragno and U. Valbusa, Phys. Rev. Lett. 86 (2001) 838.