Atypical self-activation of Ga dopant for Ge nanowire devices

Clemens Zeiner, Alois Lugstein*, Thomas Burchhart, Peter Pongratz, Justin G. Connell, Lincoln J. Lauhon, Emmerich Bertagnolli

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


In this Letter we report the atypical self-activation of gallium (Ga) implanted by focused ion beam (FIB) into germanium nanowires (Ge-NWs). By FIB implantation of 30 keV Ga+ ions at room temperature, the Ge-NW conductivity increases up to 3 orders of magnitude with increasing ion fluence. Cu3Ge heterostructures were formed by diffusion to ensure well-defined contacts to the NW and enable two point I/V measurements. Additional four point measurements prove that the conductivity enhancement emerges from the modification of the wires themselves and not from contact property modifications. The Ga distribution in the implanted Ge-NWs was measured using atom probe tomography. For high ion fluences, and beginning amorphization of the NWs, the conductivity decreases exponentially. Temperature dependent conductivity measurements show strong evidence for an in situ doping of the Ge-NWs without any further annealing. Finally the feasibility of improving the device performance of top-gated Ge-NW MOSFETs by FIB implantation was shown.

Original languageEnglish (US)
Pages (from-to)3108-3112
Number of pages5
JournalNano letters
Issue number8
StatePublished - Aug 10 2011


  • Nanowire
  • gallium
  • germanium
  • ion beam doping
  • self-activation

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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