Correlated characterization of hybrid metal-conjugated polymer nanowires
(2010)
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Details
- Authors
- Supervisors
- Bayot, Vincent
- Abstract
- (en) In recent years, investigators in industry and academia have increasingly tamed the structural and electronic properties of of low dimensional materials. Among them, nanowires (NWs) and nanotubes were intensely scrutinized because of their potential use in various applications requiring miniaturization. Besides the well-known CNT, many species of NWs-like nanomaterials can be synthesized from inorganic and/or organic materials and offer an impressive potential in applications ranging from bio-environmental sensing and energy harvesting to ultra-low power electronic devices and high density memories. Nevertheless, the use of single NW in real applications asks for identifying their intrinsic behavior and requires to manipulate and contact them properly. The aim of this thesis is to contribute to this active research area, focusing particularly on hybrid metal-polymer nanowires made of conjugated polymers (PPy, PEDOT, PANi) and metals (Au, Pt, Ni) with diameters ranging from 30 nm to 160 nm. In this experimental study, we investigated the electrical and structural properties of several classes of hybrid nanowires (HNW) and HNW arrays. The first part of this thesis, focuses on the structural and electrical characterization of several classes of HNW arrays. A careful characterization of the metal-polymer interfaces by transmission electron microscopy revealed that the structure and mechanical strength of the interfaces are very different. Variable temperature electrical transport measurements suggested that the three-dimensional Mott variablerange- hopping (VRH) model provides a complete framework for understanding charge transport, including nonlinear current-voltage characteristics and magnetotransport. The diameter dependence of the electrical properties of HNWs suggests that the transport mechanism changes for the 40 nm HNWs samples which exhibit a behavior indicative of the critical regime of disorder-induced metal-insulator transition. Then, because of the several limitations of the bulk characterization of HNWs (e.g. averaging effects on the measured properties, high contact resistance, no interactions with the environment, ...) we investigated the integration of single HNW in a planar electronic devices. Advantageously, single HNW measurements allow us to probe the responses of HNWs to different stimuli. Especially, we showed that the electrical properties of mutli-segmented HNWs can be switched chemically from a linear to a rectifying behavior. We proposed a simple model based on Schottky diodes to explain and reproduce the observed phenomenon. Finally, to gain further insight into the structure-property relationships of these nanomaterials, we developed, fabricated and characterized multipurpose platforms, fabricated via Si micromachining techniques. These microdevices enable the correlation between the structural properties -as observed, for instance, by transmission and scanning electron microscopies - the electrical and thermal properties obtained from the same sample. While these membrane-based microdevices were used for correlated studies of NWs, the extension to other nanomaterials (organic, inorganic, or hybrid films, nanoparticles) is straightforward.
- Affiliations
UCLouvain SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
Citations
Gence, L. (2010). Correlated characterization of hybrid metal-conjugated polymer nanowires. https://hdl.handle.net/2078.5/131221