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O: Fachverband Oberflächenphysik

O 37: Scanning Probe Techniques

O 37.7: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster A

Scanning Tunneling Microscopy-study of the interplay between light induced effects and tunnel current on the GaAs (110) surface — Philipp Kloth, •Katharina Kaiser, and Martin Wenderoth — IV. Physikalisches Institut, Georg-August Universität Göttingen, Germany

Using a low temperature Scanning Tunneling Microscope in combination with optical excitation we have studied the effect of the tunnel current on the surface photovoltage at the GaAs (110) surface. Spectroscopic measurements show that light-generated holes at the surface can be addressed by tunneling electrons, opening an additional tunnel channel into valence band states. Current dependent analysis reveals that this additional channel can be saturated. We have performed a detailed analysis of the saturation current as a function of the optical induced carrier density and the applied bias voltage. By changing the tunnel current we can actively switch between the dominant channel being either the optically induced channel or the common channel present under dark conditions. Moreover we show that the annihilation of holes in the valence band via the tunnel current affects the tip induced band bending at the surface.