Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014)
    Nanomaterials Tuesday Sessions
       Session NM-TuM

Paper NM-TuM12
Band Offsets at Zincblende-Wurtzite GaAs Nanowire Sidewall Surfaces

Tuesday, December 9, 2014, 11:40 am, Room Hau

Session: Nano Devices
Presenter: Philipp Ebert, Forschungszentrum Jülich GmbH, Germany
Authors: P. Capiod, Institut d’Electronique et de Microélectronique et de Nanotechnologies, France
T. Xu, Institut d’Electronique et de Microélectronique et de Nanotechnologies, France
J.P. Nys, Institut d’Electronique et de Microélectronique et de Nanotechnologies, France
M. Berthe, Institut d’Electronique et de Microélectronique et de Nanotechnologies, France
G. Patriarche, CNRS-Laboratoire de Photonique et de Nanostructures, France
L. Lymperakis, Max-Planck Institut für Eisenforschung GmbH, Germany
J. Neugebauer, Max-Planck Institut für Eisenforschung GmbH, Germany
P. Caroff, The Australian National University, Australia
R.E. Dunin-Borkowski, Forschungszentrum Jülich GmbH, Germany
P. Ebert, Forschungszentrum Jülich GmbH, Germany
B. Grandidier, Institut d’Electronique et de Microélectronique et de Nanotechnologies,, France
Correspondent: Click to Email
Recent advances in the growth of nanowires allow the fabrication of complex crystal structures, which otherwise are unstable and hence cannot be achieved in the bulk. In these semiconductor polytype materials, understanding the energetic position of surface states and Fermi level position at the surface is critical, since these parameters might govern the material transport and optical properties. However, the importance of the surface has been put aside so far, due to controversies that already exist for the band alignment in the bulk polytypes. A prototypical material is GaAs, where polytype inclusions consisting of zinc-blende (ZB) and wurtzite (WZ) segments form during the growth of NWs and where the band discontinuities at the interface are strongly debate.

Therefore, we investigated the band structure and the Fermi level pinning at clean and well-ordered sidewall surfaces of zincblende (ZB)-wurtzite (WZ) GaAs nanowires by scanning tunneling spectroscopy and density functional theory calculations. The WZ-ZB phase transition in GaAs nanowires introduces p‑i junctions at the sidewall surfaces. This is caused by the presence of numerous steps, which induce a Fermi level pinning at different energies on the non-polar WZ and ZB sidewall facets.