Dresden 2003 – wissenschaftliches Programm

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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 12.35: Poster

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

SPA–LEED and AFM investigations about the morphology of Silicon On Insulator — •M. Czubanowski, C. Tegenkamp, and H. Pfnür — Institut f. Festkörperphysik, Abtlg. Oberflächen, Universität Hannover, Appelstr. 2, D–30167 Hannover

Silicon On Insulator (SOI) is an attractive substrate for many experiments, since the thin Si(100) is insulating even at 300 K. A crucial step for in–situ experiments is the removal of the native oxide. Therefore, we tested different procedures and checked the final morphology by both SPA–LEED and AFM.
We show that the SOI structure becomes already unstable for sample temperatures higher than 1070 K, i.e annealing up to 1270 K by direct current leads to the formation of Si–clusters (width 70 nm ) with grooves of 200 nm in between, as clearly seen by AFM, although LEED reveals a brilliant pattern. Resistivity measurements prove that the buried oxide layer is partly destroyed by this treatment. Therefore, other preparation techniques have been tested to obtain smooth and continuous SOI–films. Best results were obtained by evaporation of Si at 1040 K. For Si–fluxes around 0.025 ML/s volatile SiO is formed by reaction of Si with the native oxide. The rms–roughness in this case was better than 3 Å as concluded from AFM and a G(S)–analysis done with SPA–LEED. The average terrace length Γ is around 300 Å. Similiar results were obtained by a combination of Ar–sputtering followed by annealing the sample in an oxygen background pressure (1020 K, 2× 10−8 mbar), but the roughness parameters are higher by a factor of two (Γ=160 Å, rms=7.7 Å) and pits ([113]–facets) are formed within the SOI–film.

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