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O: Oberflächenphysik

O 12: Postersitzung (Struktur und Dynamik reiner Oberfl
ächen, Grenzfl
äche fest-flüssig, Nanostrukturen, Teilchen und Cluster, Halbleiteroberfl
ächen und Grenzfl
ächen, Zeitaufgelöste Spektroskopie, Rastersondentechniken, Methodisches)

O 12.33: Poster

Montag, 24. März 2003, 18:00–21:00, P1

Surface morphology of three-dimensional Si islands on Si(001) surfaces — •Alexander Shklyaev and Volkmar Zielasek — Institut für Festkörperphysik, Universität Hannover, Appelstr. 2, D-30167 Hannover

Silicon deposition on ultrathin SiO₂ films was used for growing 3D Si islands on Si(001) substrates. The SiO₂ film promotes high density island formation during Si deposition. At growth temperatures from 450 to 570^∘C hemispherical Si islands form. While their bulk is in epitaxial registry with the Si substrate their surface structure is irregular. LEED data also show that pyramidal Si islands, growing at temperatures between 570 and 680^∘C, have predominantly {113} facets with a 3 × 1 reconstruction on the sidewalls. With increasing growth temperature, decomposition of the SiO₂ films gradually increases and the rest of SiO₂ films completely disappears at T∼640^∘C, whereas the Si pyramids are observed at temperatures up to 680^∘C. The low mobility of Si across the Si/SiO₂ boundary appears to be the main factor stabilizing the 3D Si islands against decay while the pronounced local minimum of the Si surface energy at {113} orientation is responsible for the flatness of the Si pyramid sidewalls. We have determined growth conditions for creating nanoscale Si dots with specific structural properties in Si and Si/SiO₂ matrices.