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.