Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 24: Semiconductor Substrates: Epitaxy and Growth

O 24.4: Vortrag

Dienstag, 27. März 2007, 12:00–12:15, H39

Epitaxial growth of Aluminium on Silicon (111) studied by SPA-LEED and STM — •Thomas Payer, Christian Wiethoff, and Michael Horn-von Hoegen — Universität Duisburg-Essen, FB Physik, AG Horn-von Hoegen, Lotharstraße 1 47057 Duisburg

We studied the epitaxial growth of Aluminium on Si (111) on Al-induced reconstructions as well as on the plain Si (111) (7x7) reconstruction. The film and surface morphology was studied in-situ by scanning tunnelling microscopy (STM). During deposition, the growth kinetics was observed by spot profile analyzing LEED (SPA-LEED). The deposition temperature varied between room temperature and 700K. On Si(111) Al grows in (111)-orientation. Both lattice constants of Al (111) and Si (111) fit in a 4 to 3 ratio with a small remaining mismatch of only 2%. Growth on top of the Al-induced (√3×√3) reconstruction in a temperature regime of 500 - 550 K yields the smoothest films. Compared to films directly deposited on top of the Si (111) (7x7), the film roughness is reduced by a factor of five to 2nm rms roughness for a 20nm thick film. Growth on top of other Al-induced reconstructions do not provide any advantages in comparison to deposition on top of the clean Si (111) (7x7) surface. Instead, islands are formed and the films show an enhanced surface roughness. Growth at temperatures above 600K results in a Stransky-Krastanov mode with large Al islands on the Al-induced γ-reconstruction.