Carbon tips as electrodes for single-molecule junctions

Abstract

The following article appeared in Applied Physics Letters vol 99,12 (2011): 123105 and may be found at http://scitation.aip.org/content/aip/journal/apl/99/12/10.1063/1.3643031?showFTTab=true&containerItemId=content/aip/journal/aplWe study electron transport through single-molecule junctions formed by an octanethiol molecule bonded with the thiol anchoring group to a goldelectrode and the opposing methyl endgroup to a carbon tip. Using the scanning tunneling microscope based break junction technique, we measure the electrical conductance of such molecular junctions. We observe the presence of well-defined conductance plateaus during the stretching of the molecular bridge, which is the signature of the formation of a molecular junction.Acknowledges fellowship support from the Comunidad de Madrid (Spain). This work was supported by MICINN (Spain) through the programs MAT2008-01735 and CONSOLIDER-INGENIO-2010 CSD-2007-00010, by Comunidad de Madrid through the program NANOBIOMAGNET S2009/MAT1726, by the EU through the networks BIMORE (MRTN-CT-2006-035859),and by the EC through the network FP7 ITN “FUNMOLS”Project Number 212942

Carbon tips for all-carbon single-molecule electronics

“…It is worth commenting the connection between our results and the experiments of Castellanos-Gomez 15,39 where molecular junctions were formed between carbon tips and octanethiol self-assembled monolayers. In those experiments, the appearance of rather short plateaus was reported, which was tentatively attributed to the formation of a chemical bond between the tip and the non-thiolated end of the molecule.…”

“…16 The presence of hydrogen atoms ensures the stability of the graphitic tip reducing its reactivity with possible contamination. The H atoms were introduced here to mimic the experimental conditions of the work of Castellanos-Gomez et al 15 The electronic structure of this tip, and of all the systems studied in this work, was described using a very efficient density functional theory (DFT) molecular dynamics technique (FIREBALL). 17,18 The FIREBALL package uses a localized optimized minimal basis set, 19 and the self-consistency is achieved over the occupation numbers through the Harris functional.…”

“…Although this approach has opened fascinating possibilities, it also has some disadvantages such as the inability to control the metal-molecule distance in situ. An alternative to the SWNTs has been recently provided by Castellanos-Gomez et al 15 who have shown that carbon ber tips can be used to form singlemolecule junctions in the spirit of STM-based break junctions. In particular, these authors have applied the carbon ber tips in molecular junctions with monothiolated alkane chains, something that is not easy to realize using gold electrodes.…”

Carbon-fiber tips for scanning probe microscopes and molecular electronics experiments

“…Here, we have explored the use of carbon-based tips as contact electrodes to form molecular junctions [ 3 ]. Using the scanning tunneling microscope (STM) break-junction technique, we have measured the electrical conductance of several hundreds of octanethiol-based single-molecule bridges (CH 3 -C 7 H 14 -SH) in which the thiol anchoring group is bound to a gold electrode, and the methyl group is linked to a carbon electrode.…”

Lithography-free electrical transport measurements on 2D materials by direct microprobing

“…The electrical probes are made out of polyacrylonitrile (PAN) carbon fibers [24][25][26][27] ~1 mm long. We address the reader to the Supporting Information for a characterization of the fiber electrical resistivity and contact resistance 28 .…”