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HL: Fachverband Halbleiterphysik

HL 75: Poster IIIB

HL 75.16: Poster

Donnerstag, 19. März 2020, 15:00–17:30, P2/3OG

Multi-probe electrical characterization of pn-GaAs-based nanowires under illumination — •Juliane Koch, Andreas Nägelein, Matthias Steidl, Peter Kleinschmidt, and Thomas Hannappel — TU Ilmenau, Institute for Physics, Fundamentals of Energy Materials, Ilmenau, Germany

Semiconducting nanowires (NW) are known as promising candidates for a large variety of future optoelectronic devices, such as for solar energy conversion devices. For their beneficial use it is essential to control doping profiles along the NW with abrupt charge-separating contacts and to assess their optoelectronic performance. This can be achieved by appropriate electronic and optoelectronic characterization. In this work, a multi-tip scanning tunneling microscope (MT-STM), which is equipped with a scanning electron microscope (SEM), enables the independent control of four tungsten-tips, which are employed to perform 2- and 4-point I-V-measurements on individual, freestanding NWs with high spatial resolution. We were able to to record measurements on NW comprising pn-junctions, both with and without illumination. The resulting resistance profiles without illumination provide direct access to the doping profiles, so that the doping concentration of the p- and the n-doped region can be determined as well as the position of the charge-separating contact. Measurements under illumination yields the photocurrent as well as the fill factor associated with the I-V characteristic of the illuminated NW. In addition, the charge-separating contact can be visualized in the SEM by detection of the electron beam induced current.