Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 21: III-V semiconductors II
HL 21.1: Vortrag
Dienstag, 27. März 2007, 11:00–11:15, H17
The Mn Acceptor in InAs: Depth-Dependent Shape and Supression of the Conduction Band — Jens Wiebe1, •Felix Marczinowski1, Jian-Ming Tang2, Michael E. Flatté2, Markus Morgenstern3, and Roland Wiesendanger1 — 1Institut für Angewandte Physik, Universität Hamburg — 2Optical Science and Technology Center and Department of Physics and Astronomy, University of Iowa, USA — 3II. Institut für Physik B, RWTH Aachen
Recent work using scanning tunneling spectroscopy (STS) revealed that acceptors in III/V semiconductors appear strongly anisotropic and their mirror asymmetry regarding the (001) plane depends on the binding energy Eb. While the energetically deep acceptor Mn in GaAs has a symmetric cross like shape [1], shallow acceptors like Zn show an asymmetric triangular feature [2]. We analyzed the relatively deep acceptor Mn in InAs (Eb=30meV) by STS and find a dependency of the shape on the depth below the (110) surface. Deeper Mn acceptors appear as a cross with a low asymmetry which is reproduced by a bulk tight-binding model (TBM). Mn acceptors closer to the surface show a strong asymmetry of the cross resulting in a triangular feature. A possible explanation is the strengthening of the asymmetry by surface relaxation. The influence of the acceptor on the conduction band (CB) has also been studied by STS and TBM calculations. The CB density of states shows a supression close to the Mn which is surrounded by an oscillation reflecting the anisotropy of the acceptor state.
[1] A. M. Yakunin et al., Phys. Rev. Lett. 92, 216806 (2004)
[2] S. Loth et al., Phys. Rev. Lett. 96, 066403 (2006)