title: Atypical self-activation of Ga dopant for Ge nanowire devices.
abstract: 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. Cu(3)Ge 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.
authors: Institute for Solid State Electronics, Vienna University of Technology, Vienna, Austria.
authors: Clemens
authors: C
authors: Zeiner
authors: Alois
authors: A
authors: Lugstein
authors: Thomas
authors: T
authors: Burchhart
authors: Peter
authors: P
authors: Pongratz
authors: Justin G
authors: JG
authors: Connell
authors: Lincoln J
authors: LJ
authors: Lauhon
authors: Emmerich
authors: E
authors: Bertagnolli