Hamburg 2001 – wissenschaftliches Programm
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O: Oberflächenphysik
O 18: Halbleiteroberfl
ächen und -grenzfl
ächen
O 18.6: Vortrag
Dienstag, 27. März 2001, 12:30–12:45, M
Subsurface Dimerization in III-V Compound Semiconductor (001)-Surfaces — •Christian Kumpf1, Detlef Smilgies1, Erik Landemark1, Mourits Nielsen1, Oliver Bunk2, Jan H. Zeysing2, Yixi Su2, Robert L. Johnson2, Jörg Zegenhagen3, and Robert Feidenhans’l1 — 1Condensed Matter Physics and Chemistry Department, Risø National Laboratory, Denmark — 2II. Institut für Experimentalphysik, Universität Hamburg, Germany — 3European Synchrotron Radiation Facility, France
The (001)-surfaces of III-V compound semiconductors show a wealth of surface reconstructions that play an important role in both homo and heteroepitaxial growth. It is generally believed that the basic building blocks in these reconstructions consist of group III or group V dimers. For the group V rich surfaces, group V dimers have been clearly identified by STM. But for the group-III rich surface it has not been possible to uniquely identify the features attributed to dimers as really being made up of two atoms. We show that dimers at the surface are not the central element of the group III rich surfaces but sub-surface dimerization in the second bilayer, accompanied by linear arrangement of group III atoms in the top layer. A completely new model, based on surface x-ray diffraction results on three sample types (GaAs, InAs and InSb), is presented. To our knowledge it is the first time that one unique model has been found for three different sample types. Independently from us for one of these surfaces, GaAs, a very similar model has been found recently by means of total energy calculations and LEED (S.-H. Lee et al., Phys. Rev. Lett. 85 (2000) 3890).