  In this paper, we report on the impact of metal/polymer interfaces on the
rectifying behavior of novel multi-segmented hybrid nanowires (HNWs) made of
metallic and conjugated polymer (CP) segments. Using HNWs integrated in
micromachined devices, the relationship between electronic properties and
original structure is revealed. By combining transmission electron microscopy
(TEM) and current-voltage (I-V) spectroscopy studies performed on several
symmetric and asymmetric HNWs structures, we show that rectifying I-V
characteristics are observed only for asymmetric HNWs. Moreover, it is shown
that the rectification ratio can be improved up to 3 orders of magnitude by a
proper selection of the HNW composition. While the rectifying behavior is
observed in HNWs after oxidative or acid doping, the charge transport mechanism
in as-synthesized HNWs is bulk-limited and independent from their structure.
Both symmetric and asymmetric HNWs exhibit Ohmic and non-linear I-V curves
above and below T~120 K, respectively. These electrical behaviors are
consistent with a smooth transition from an Ohmic to a non-Ohmic
variable-range-hopping (VRH) mechanism. We discuss the origin of these
nonlinearities comparing the two- and four-probe measurements on single HNWs
and we propose a simple model based on dual back-to-back Schottky diodes to
explain qualitatively the rectifying properties.
