Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 5: Electronic structure I
O 5.3: Vortrag
Montag, 27. März 2006, 11:45–12:00, WIL A317
Electronic structure of the 6H-SiC(1120) non-polar surface — •Marco Bertelli1, Jan Homoth1, Martin Wenderoth1, Rainer G. Ulbrich1, Angela Rizzi1, M. Clelia Righi2, and Alessandra Catellani3 — 1IV. Physikalisches Institut, Georg-August Universität Göttingen, Germany — 2CNR-INFM National Center on nanoStructures and bioSystems at Surfaces (S3) and Dipartimento di Fisica, Università di Modena e Reggio Emilia, Modena, Italy — 3CNR-IMEM, Parco Area delle Scienze, Parma, Italy and S3
We studied the 6H-SiC(1120) surface reconstruction by means of combined cross-section scanning tunneling microscopy and ab-initio simulations. The n-doped Si-terminated 6H-SiC(0001) substrates were cleaved in ultra high vacuum and measured in-situ by STM at room temperature. The experimental results show an unreconstructed surface. The surface unit cell resembles the stacking sequence of the 6H polytype. The most prominent feature in the occupied state images within the cell is a depression at the inversion point.
In agreement with the experimental observation, the theoretical calculations predict a relaxed surface, but no reconstruction. Correspondingly bond lengths and angles change along the stacking sequence only for the outermost layer, with Si atoms moving inwards of ca. 0.22 Å. C atoms positions are almost unchanged, but for a depression of 0.07 Å at inversion. In general, the up and down arrangement of C and Si atoms is responsible for the observed features in STM images: filled states appear to be concentrated on the carbon atoms and the empty states on the Si atoms.