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O: Fachverband Oberflächenphysik

O 21: Clean surfaces: Metals, semiconductors, oxides and insulators II

O 21.5: Talk

Monday, March 14, 2011, 18:15–18:30, WIL B122

Anomalous double layer step formation on Si(100) in hydrogen ambient — •Henning Döscher, Peter Kleinschmidt, Anja Dobrich, Sebastian Brückner, Oliver Supplie, Johannes Luczak, and Thomas Hannappel — Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany

Generation of double layer steps on Si(100) is desirable for subsequent anti-phase domain-free heteroepitaxy of III-V semiconductors. In UHV established procedures exist for the formation of double layer steps at the clean Si(100) surface. In the (metal-organic) vapour phase epitaxy environment the situation is more complicated due to the presence of hydrogen in the process ambient. Both theory and experiment of the hydrogenated surfaces suggest that under equilibrium conditions no preference for double layer steps is to be expected. Previously, we have shown that annealing in hydrogen at near atmospheric pressure leads to termination of the surface by monohydride. Here, we show that a process using Si(100) with an intermediate offcut of 2^∘ in <011> can lead to a double layer stepped surface. Our process consists of deoxidation, homoepitaxial growth employing silane, annealing and slow cooling to 500^∘C in hydrogen ambient. We observe the formation of double layer steps using Fourier-transform infrared spectroscopy, low-energy electron diffraction and scanning tunneling microscopy. In sharp contrast to established UHV results, the double layer steps are of the D_A type, where dimer rows of the reconstructed surface are parallel to the step edges.