Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 56: [DS] Progress in Micro- and Nanopatterning: Techniques and Applications III (Focused Session, jointly with O - Organisers: Graaf, Hartmann)

O 56.7: Vortrag

Mittwoch, 16. März 2011, 16:30–16:45, GER 38

Surfactant driven self-organized surface patterns by ion beam erosion — •Hans Hofsäss and Kun Zhang — II. Physikalisches Institut, Universität Göttingen, 37077 Göttingen, Germany

Self-organized pattern formation on surfaces by ion beam erosion and driven by metal surfactant atoms is discussed. Si substrates were irradiated with 5 keV Xe ions at normal incidence and ion fluences up to 5x10¹⁷ Xe⁺/cm² under continuous deposition of surfactant atoms. In the absence of surfactants uniform flat surfaces are obtained. With surfactants pronounced patterns like dots, combinations of dots and ripples as well as ripples with about 100 nm wavelength are generated. 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 between about 10¹⁵ and 5x10¹⁵ atoms/cm². With increasing ion fluence the pattern contrast increases but the pattern type remains unchanged. The 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. Directed deposition of metal surfactant causes preferential deposition and shadowing and determines the final pattern orientation and morphology. First results on the dynamic behaviour of the ripples are presented.