Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 21: III-V semiconductors II

HL 21.7: Talk

Tuesday, March 27, 2007, 12:30–12:45, H17

Scanning Tunneling Spectroscopy of Si donors in GaAs {110} — •K. Teichmann, M. Wenderoth, S. Loth, and R. G. Ulbrich — Universität Göttingen, IV. Physikalisches Institut, Germany

Silicon donors in highly n-doped GaAs (6.5×10¹⁸cm⁻³) are investigated by Cross-Sectional Scanning Tunneling Microscopy in UHV at 8K. Donors near the surface of the {110} cleavage planes are studied by spatially resolved I(V)-spectroscopy.

The dopant atoms are identified by their bias dependent topographic and spectroscopic properties. In addition to the known features at negative and small positive voltages, our measurements on single donors show an additional transport channel for larger positive bias voltages. The current distribution has a circular symmetric structure. The diameter is bias dependent, and can extend up to several nanometers around the donor. The minimal bias voltage of the current onset is localized above the donors. We discuss different scenarios - including tip induced band bending - that can lead to the observed ring-like shapes.

This work was supported by the DFG, SFB 602.