Berlin 2012 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 38: Poster III: Resistive switching (jointly with DF, KR, HL); Thermoelectric materials (Focused session); Micro- and nanopatterning (jointly with O); Ion irradiation effects
DS 38.30: Poster
Donnerstag, 29. März 2012, 17:30–19:00, Poster E
Influence of Phase Separation for Surfactant Driven Pattern Formation during Ion Beam Erosion — Hans Hofsäss, •Kun Zhang, Ulrich Vetter, Omar Bobes, Andre Pape, Hans-Gregor Gehrke, and Marc Brötzmann — II. Phys. Institut, Uni Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
We will present results on metal surfactant driven self-organized pattern formation on surfaces by ion beam erosion, with a focus on the role of phase separation for the initial steps of pattern formation. Si substrates were irradiated with 5 keV Xe ions at normal incidence and ion fluences up to 5*1017 Xe/cm2 under continuous deposition of surfactant atoms. In the absence of such surfactants uniform flat surfaces are obtained, while in the presence of Fe and Mo surfactants pronounced patterns like dots, combinations of dots and ripples with wavelengths around 100 nm are generated [1]. The surfactant coverage and deposition direction determine the pattern type and the pattern orientation, respectively. A critical steady-state coverage for onset of dot formation and onset of ripple formation is in the range of 1015 and 5*1015 /cm2. The steady-state surface region consists of a thin amorphous metal silicide layer with high metal concentration in the ripple and dot regions. Pattern formation is explained by ion induced diffusion and phase separation of the initially flat amorphous silicide layer and subsequent ion beam erosion with composition dependent sputter yield. To investigate the role of initial phase separation we additionally compare the pattern formation for different other metal surfactants. [1] H. Hofsäss et al., New J. Phys. 13 (2011) 013033