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O: Fachverband Oberflächenphysik

O 7: Semiconductor substrates

O 7.5: Vortrag

Montag, 23. März 2009, 12:15–12:30, SCH A315

Ge nanoisland growth on the In/Si(112)-"(3.5×1)" surface — •Moritz Speckmann, Thomas Schmidt, Jan Ingo Flege, Torsten Wilkens, and Jens Falta — Institute of Solid State Physics, University of Bremen, 28359 Bremen

In this work we investigated the adsorption of In on Si(112) and the subsequent growth of Ge islands using a variety of different surface sensitive techniques. The unstable Si(112) surface consists of (111)- and (337)-like facets in [110] direction (Baski et al., PRL, 74 (1995) 956). The surface is smoothened due to the adsorption of metals, such as Ga or In (Snijders et al., PRB, 72 (2005) 125343).

In LEED images we find an incommensurate "(3.5×1)" reconstruction for the In/Si(112) surface. We determine the number and the positions of the In atoms inside one unit cell using XPS and X-Ray Standing Waves (XSW). With these results it is, for the first time, possible to propose a structural model based on direct structural data.

By means of Low Energy Electron Microscopy (LEEM) and Photoemission Electron Microscopy (PEEM) we monitored the growth of Ge on the In/Si(112) surface. First a smooth wetting layer is formed and after a few MLs islands start to grow. The observed islands are triangularly shaped with a longer edge along the [110] direction. The island density is higher compared to the growth on bare Si(112). Moreover no arrangement or preferential direction is visible for Ge islands on the bare Si(112) surface. The corresponding LEED patterns reveal a (4×1) reconstruction with additional facet spots which are attributed to the Ge islands.