Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 46: Poster 2
HL 46.30: Poster
Donnerstag, 29. März 2007, 15:00–17:30, Poster A
Tunneling Transport Involving Evanescent States in III-V Semiconductors — S. Loth1, M. Wenderoth1, •S. Siewers1, K. Teichmann1, L. Winking1, R. G. Ulbrich1, S. Malzer2, and G. H. Döhler2 — 1Universität Göttingen, IV. Physikalisches Institut, Germany — 2Universität Erlangen-Nürnberg, Max-Planck-Research Group, Institute of Optics, Information, and Photonics, Germany
Shallow acceptors near the {110} cleavage surfaces of III-V semiconductors are investigated with a Cross-Sectional Tunneling Microscope at 8K. For certain tunneling conditions the acceptors appear as distinct triangular protrusions in the STM images. Energetically and spatially resolved spectroscopies show that the pronounced anisotropic contrast pattern are due to a tunneling process involving evanescent states in the fundamental band gap of the semiconductor. The dopant atom enhances this transport channel via the resonant tunneling device geometry and provides an energy filter. The lateral resolution of the STM gives access to the spatial and directional dependence of this transport process. To study the properties of this transport mechanism the electronic configuration around the acceptor atom is varied by changing the doping surroundings and using different host materials. Our data indicate that not only the real part but also the complex part of the bulk band structure together with large k-dependent splittings have to be taken into account in the interpretation of STM data.
This work was supported by the DFG, SFB 602, and the German National Academic Foundation.