Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 3: III-V semiconductors I
HL 3.6: Vortrag
Montag, 27. März 2006, 11:30–11:45, POT 51
Resonant Tunneling through space-charge layers at GaAs surfaces — •S. Loth1, M. Wenderoth1, 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
Recent work in the field of the tunneling magneto resistance showed that charge transport through tunnel junctions has to be treated beyond Bardeen’s basic model: the tunnel process must be described within the framework of the complex band structure [1]. Usually this approach is not necessary for the interpretation of Scanning Tunneling Microscope (STM) measurements, because the current is mediated by real states in the sample and by evanescent states only in the vacuum gap. We demonstrate that for a class of well known experiments - Scanning Tunneling Spectroscopy (STS) on GaAs - the evanescent gap states are most relevant:
We studied p-doped GaAs {110} cleavage surfaces with a low temperature STM. The observed negative differential conductivity is due to a resonant enhancement of the tunneling probability through the depletion layer mediated by individual shallow acceptors. Energetically and spatially resolved spectra show that the pronounced anisotropic contrast pattern of shallow acceptors occurs exclusively for the energy interval of this specific transport channel. Our results indicate that structural properties of the complex band structure can be probed with the STM.
[1] P. Mavropoulos et al., Phys. Rev. Lett. 85, 1088 (2000).