Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Poster Monday: Nanostructures

O 18.10: Poster

Montag, 1. April 2019, 17:45–20:00, Poster F

Surface dependent analysis of freestanding GaAs-nanowires — •Andreas Nägelein¹, Juliane Koch¹, Matthias Steidl¹, Stefan Korte², Bert Voigtländer², Peter Kleinschmidt¹, and Thomas Hannappel¹ — ¹Institute of Physics, TU Ilmenau, 98693 Ilmenau, Germany — ²Peter Grünberg Institut (PGI-3,) Forschungszentrum Jülich, 52425 Jülich, Germany

Nanostructures e.g. III-V nanowires (NW) are known as promising candidates for optoelectronic applications. In this work we investigate single, freestanding "vapor liquid solid" (VLS) grown GaAs-NWs by a multi-tip scanning tunneling microscope (MT-STM). Here, four-point probe measurements are performed non-destructively by contacting three tips at the nanowire and using the substrate as a fourth contact. Besides the investigation of doping profiles, a comparison between nanowires prior to and after oxidation was carried out. The resistance slope in the intrinsic part of the NW increased drastically with oxidation. In contrast to doped NW-parts where the charge carrier transport mainly takes place in the center of a NW, a conductive channel does not exist for intrinsic NWs. Besides contamination-induced band bending, the conductivity is also affected by the surface states themselves. Since oxidation changes the surface states and thereby the space charge layer, we consider a changed surface conductivity of the intrinsic nanowire segment as a likely explanation of its increased resistance after exposure to ambient atmosphere.