Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 22: Epitaxie und Wachstum I

O 22.9: Vortrag

Dienstag, 25. März 2003, 17:00–17:15, FOE/ORG

Temperature induced changes of Ga/Si(111) surface reconstruction studied by STM — •Subhashis Gangopadhyay, Thomas Schmidt, and Jens Falta — Institute for Solid State Physics, University of Bremen, P. O. Box 330440, Bremen 28334, Germany

The temperature dependent phase transitions of Ga induced surface reconstructions on Si(111) have been investigated by means of variable temperature STM between room temperature (RT) and 500^∘C. RT-deposition of 1/3 ML of Ga on Si(111) surface leads to the formation of Ga induced self organized magic clusters in a 7×7 like arrangement within the domains of the initial Si(111)-7×7 surface whereas Ga-islands are found near the domain boundary regions. The magic clusters are thermally stable up to 400^∘C. At this temperature the magic clusters start to break and form patches of √3×√3-Ga and Si(111)-7×7 reconstruction. The Ga-islands however are less stable and with temperature increase near 300^∘C island coalescence is observed. At about 350^∘C mostly 6.3×6.3-Ga structure with few patches of √3×√3-Ga is found near the domain boundaries. At 400^∘C a change of the surface structure from √3×√3-Ga to 6.3×6.3-Ga is found in this region which is opposite to the usual phase sequence of Ga-Si(111) surface reconstruction. Initial studies of Ge growth on this surface will also be discussed.