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Measurements of low-conductance single molecules using gold nanoelectrodes: limitations and considerations
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. (Nanoteknologi och Funktionella Material)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics. (Elektronmikroskopi och Nanoteknologi)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics. (Elektronmikroskopi och Nanoteknologi)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. (Nanoteknologi och Funktionella Material)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

A high resistance nanogap platform was used to trap and electrically characterize 30 nm thiolated double-stranded DNA molecules. High resolution scanning electron microscopy was also used to image the trapped DNA strands. It was found that the surface state of the electrodes and underlying substrate could influence the measurements of trapped molecules when measured resistances were on the order of TW or greater. Hydrophilic surfaces gave rise to larger leakage currents that could potentially mask underlying signals from molecules positioned in the nanogap. Finally, careful handling of the samples and control of the environment is essential to avoid surface charging of the oxide substrate layer as these parasitic charges affect electrical measurements of the nanogap. The presented results should be useful for characterization of molecules in molecular electronics or sensors employing nanogap platforms.

Keyword [en]
Nanogap, nanoelectrode, DNA, molecular electronics, surface charge
National Category
Nano Technology
Identifiers
URN: urn:nbn:se:uu:diva-122949OAI: oai:DiVA.org:uu-122949DiVA: diva2:311480
Available from: 2010-04-21 Created: 2010-04-21 Last updated: 2012-12-07
In thesis
1. Fabrication and Applications of a Focused Ion Beam Based Nanocontact Platform for Electrical Characterization of Molecules and Particles
Open this publication in new window or tab >>Fabrication and Applications of a Focused Ion Beam Based Nanocontact Platform for Electrical Characterization of Molecules and Particles
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The development of new materials with novel properties plays an important role in improving our lives and welfare. Research in Nanotechnology can provide e.g. cheaper and smarter materials in applications such as energy storage and sensors. In order for this development to proceed, we need to be able to characterize the material properties at the nano-, and even the atomic scale. The ultimate goal is to be able to tailor them according to our needs.

One of the great challenges concerning the characterization of nano-sized objects is how to achieve the physical contact to them. This thesis is focused on the contacting of nanoobjects with the aim of electrically characterizing them and subsequently understanding their electrical properties. The analyzed nanoobjects are carbon nanosheets, nanotetrapods, nanoparticles and molecular systems.

Two contacting strategies were employed in this thesis. The first strategy involved the development of a focused ion beam (FIB) based nanocontact platform. The platform consists of gold nanoelectrodes, having nanogaps of 10-30 nm, on top of an insulating substrate. Gold nanoparticles, double-stranded DNA and cadmium telluride nanotetrapods have been trapped in the gaps by using dielectrophoresis. In certain studies, the gold electrodes have also been coated with conducting or non-conducting molecules, prior to the trapping of gold nanoparticles, in order to form molecular junctions. These junctions were subsequently electrically characterized to evaluate the conduction properties of these molecular systems. For the purpose of better controlling the attachment of molecules to the nanoelectrodes, a novel route to synthesize alkanedithiol coated gold nanoparticles was developed. The second contacting strategy was based on the versatility of the FIB instrument as a platform for in-situ manipulation and electrical characterization of non-functionalized and functionalized carbon nanosheets, where it was found that the functionalized samples had an increased conductivity by more than one order of magnitude.

Both contacting strategies proved to be valuable for building knowledge around contacting and electrical characterization of nanoobjects

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 88 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 745
Keyword
Focused Ion Beam, FIB, Scanning Electron Microscopy, SEM, Nanogap electrodes, Nanostructuring, Nanofabrication, Electron Beam Lithography, Electrical characterization, Dielectrophoresis
Identifiers
urn:nbn:se:uu:diva-122940 (URN)978-91-554-7809-4 (ISBN)
Public defence
2010-06-07, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, 75121, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2010-05-17 Created: 2010-04-21 Last updated: 2010-05-18Bibliographically approved

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Blom, Tobias

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