Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 70: Nanostructures at Surfaces: Other Aspects

O 70.8: Poster

Mittwoch, 9. März 2016, 18:15–20:30, Poster A

Controlling and monitoring the local charge distribution of a nanoscaled space charge region — •Katharina Kaiser, Philipp Kloth, and Martin Wenderoth — IV. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen

Using a low temperature Scanning Tunneling Microscope in combination with optical excitation we have investigated the interplay and dynamics of free and bound charge carriers inside a nanoscaled space charge region (SCR) at the GaAs(110) surface [1]. This approach allows us to actively modify the local charge distribution at the surface by changing the optical excitation density and the tunnel current and to control charge fluctuations.

One central part is the capture process of photo-generated minority charge carriers in the presence of locally fixed dopant atoms within the space charge region. By establishing a quantitative model, we are able to extract key quantities like the diffusive or field driven capture rate of photo-generated holes. The analysis of the noise of the tunnel current provides access to the temporal charging and discharging process of dopant atoms inside the SCR, showing that the presence of photo-generated charge carriers changes the noise of the system significantly.

[1] Kloth et al., Nat. Comm. (2015)