Hamburg 2001 – wissenschaftliches Programm

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O: Oberflächenphysik

O 25: Postersitzung (Grenzfl
äche fest-flüssig, Methodisches, Nanostrukturen, Organische Dünnschichten, Rastersondentechniken, reine Oberfl
ächen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie, Sonstiges)

O 25.17: Poster

Mittwoch, 28. März 2001, 15:00–18:00, Foyer zu B

Formation of Ge clusters on line-shaped Si(001) windows in ultrathin SiO₂ films — •V. Zielasek^1,2, A.A. Shklyaev³, and M. Ichikawa³ — ¹Joint Research Center for Atom Technology, National Institute for Advanced Interdisciplinary Research — ²Institut für Festkörperphysik, Universität Hannover, Appelstr. 2, 30167 Hannover — ³Joint Research Center for Atom Technology, Angstrom Technology Partnership, 1-1-4 Higashi, Tsukuba, Ibaraki 305-0046, Japan

We have studied the formation of Ge islands on line-shaped Si(001) windows in ultrathin (0.3 nm) SiO₂ films, using a combination of STM and scanning reflection electron microscopy. Line-shaped Si(001) window areas with a width in the range 20 to 100 nm were created by electron beam-stimulated oxygen desorption followed by selective thermal decomposition of the oxide [1]. Molecular beam deposition of Ge leads to the formation of isolated Ge nanoislands on the oxide. Confined to the window areas, coherent pyramidal (113)-facetted islands are observed after Ge deposition of > 4 monolayers at temperatures < 550^o C. In contrast to deposition on unmasked Si(001), (105)-facetted hut clusters form only after annealing the surface to > 650^o C. At these temperatures the oxide mask dissolves rapidly because of chemical reaction with Germanium and material transport across the window borders sets in, leading to the formation of incoherent macroclusters. Hut clusters are located as remains of decaying pyramidal clusters along the former Si(001) window areas. This work has been supported by NEDO. [1] M. Ichikawa, J.Phys.: Condens. Matter 11 (1999) 9861.