Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 53: Nanostructures at Surfaces: Other Aspects

O 53.3: Poster

Dienstag, 21. März 2017, 18:30–20:30, P1C

Controlling charge fluctuations of a few donor system — •Ole Bunjes, Philipp Kloth, Judith von der Haar, and Martin Wenderoth — IV. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

Combining a low temperature Scanning Tunneling Microscope with optical excitation, we have investigated temporal charge fluctuations within the tip induced space charge region. Our studies on the (110) surface of n-doped GaAs have shown that the system can be driven into different non-equilibrium states due to optically induced minority charge carriers [1]. Analysis of the noise characteristic of the tunnel current reveals the influence of photo-generated holes on dynamical charging processes. The presence of these free charges allows us to change and control the noise characteristic of the system. The noise level depends on the laser intensity as well as the tunnel current, controlled by the tip-sample-distance. Most surprisingly, the overall noise can even be reduced compared to the non-illuminated system. We attribute the optically induced modification of the noise characteristic to temporal charging and discharging of dopant atoms within the space charge region [2]. We acknowledge the financial support by the SFB1073 C04. [1] P. Kloth et al., Nat. Commun. 7, 10108 (2016) [2] K. Teichmann et al., Nano Lett. 11, 3538-3542 (2011)