Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 83: Heterostructures and Interfaces

O 83.4: Vortrag

Donnerstag, 10. März 2016, 10:15–10:30, H17

How can band offsets in III-V nanowires be determined correctly by scanning tunneling spectroscopy? — •Philipp Ebert¹, Pierre Capiod², Tau Xu², Adrian Díaz Álvarez², Xiang-Lei Han², David Troadec², Jean-Philippe Nys², Maxime Berthe², Liverios Lymperakis³, Jörg Neugebauer³, Isabelle Lefebvre², Sébastien Plissard^2,4, Philippe Caroff^2,5, Rafal Dunin-Borkowski¹, and Bruno Grandidier² — ¹Peter Grünberg Institut, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany — ²IEMN, CNRS, UMR 8520, Dept. ISEN, 59046 Lille, France — ³Max-Planck Institut für Eisenforschung GmbH, 40237 Düsseldorf, Germany — ⁴CNRS-LAAS, Univ. de Toulouse, 31400 Toulouse, France — ⁵Dept. of Electronic Materials Engineering, Australian National University, Canberra, ACT 0200, Australia

Scanning tunneling spectroscopy (STS) allows the determination of band gaps and band offsets at interfaces between different polytypes or materials of III-V semiconductor nanowires (NWs). However, STS is mostly wrongly interpreted in literature: The commonly high step density at the sidewall surfaces of III-V NWs leads to extrinsic surface states that induce a pinning of the Fermi energy within the fundamental band gap. Since the pinning level is different on every polytype/material, the relative band edge positions between different NW segments are extrinsically determined. Therefore, we developed a new methodology to accurately determine band offsets between different NW segments by using a thin overgrown shell with wider band gap, assuring identical pinning of the overgrown and the pure segment.