Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 68: Semiconductor substrates: Epitaxy and growth

O 68.1: Talk

Thursday, March 25, 2010, 10:30–10:45, H42

Dimer Flipping at the MOVPE-prepared P-rich GaP(100) Surface — •Peter Kleinschmidt, Henning Döscher, Sebastian Brückner, Anja Dobrich, Oliver Supplie, Christian Höhn, and Thomas Hannappel — Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany

The structure of the P-rich GaP(100) surface has been known for some time, showing a p(2x2)/c(4x2) reconstruction. The surface is terminated by alternating buckled phosphorus dimers stabilized by one hydrogen atom per dimer. The STM image of this surface consists of zigzag dimer chains where neighbouring chains can be aligned in phase as well as out of phase to each other. The in-phase configuration results in a p(2x2) surface unit cell, while the out-of-phase configuration corresponds to a c(4x2) unit cell.

We prepared the P-rich GaP(100) surface in a commercial MOVPE system and employed a dedicated transfer system, which enables contamination-free transfer from the MOVPE environment to UHV and, using a mobile transfer chamber, to various surface analysis systems including STM. The quality of our STM images enabled us to compare successive images, revealing in some locations flipping of the P-dimers and therefore of the surface reconstruction. This process requires shifting of the H-termination between the P-atoms in the respective dimer. It could be thermally activated, not dissimilar to the dimer flipping on the clean Si(100) surface, where the flipping cannot be resolved at room temperature by STM, or tip-induced, similar to systems where manipulation of surface atoms can be achieved.