Electrical properties and mechanical stability of anchoring groups for single-molecule electronics

We report on an experimental investigation of transport through single molecules, trapped between two gold nano-electrodes fabricated with the mechanically controlled break junction (MCBJ) technique. The four molecules studied share the same core structure, namely oligo(phenylene ethynylene) (OPE3), while having different aurophilic anchoring...

Charge transport in a zinc-porphyrin single-molecule junction

We have investigated charge transport in ZnTPPdT-Pyr (TPPdT: 5,15-di(p-thiolphenyl)-10,20-di(p-tolyl)porphyrin) molecular junctions using the lithographic mechanically controllable break-junction (MCBJ) technique at room temperature and cryogenic temperature (6 K). We combined low-bias statistical measurements with spectroscopy of the molecular...

A versatile low-temperature setup for the electrical characterization of single-molecule junctions

We present a modular high-vacuum setup for the electrical characterization of single molecules down to liquid helium temperatures. The experimental design is based on microfabricated mechanically controllable break junctions, which offer control over the distance of two electrodes via the bending of a flexible substrate. The actuator part of the...

Charge transport through single molecules in two- and three-terminal mechanical break junctions

During the past decades the downscaling of integrated circuits has been governed by Moore's law, which predicts device dimensions on the order of 10 nm in 2020. Fundamental research in molecular electronics explores the possibility of fabricating such nanoscale devices from single molecules, which offer the prospects of chemical tunability and...

Self-consistent theory of molecular switching

We study the model of a molecular switch comprised of a molecule with a soft vibrational degree of freedom coupled to metallic leads. In the presence of strong electron-ion interaction, different charge states of the molecule correspond to substantially different ionic configurations, which can lead to very slow switching between energetically...

High intra-chain hole mobility on molecular wires of ladder type poly(p-phenylenes)

The high frequency mobility of charge carriers on isolated ladder-type polymer chains with lengths ranging from 13 to 54 monomer units was measured. Experiments were performed on isolated chains in dilute solution and on bulk solid samples. The ac mobility of charge carriers measured at a microwave frequency near 30 GHz is strongly dependent on...

Electrical transport measurements on self-assembled organic molecular wires

The electrical properties of supermolecular assemblies of oligo(p-phenylene vinylene) were studied. These materials self-assemble into well-defined cylindrical structures in solution with lengths in the range of 100?nm–10??m and diameters between 5 and 200?nm. Atomic force microscopy showed that by adjusting the concentration, either individual...

Noise and Spin in Nanostructures

Fault-tolerant architectures for nanoelectronic and quantum devices

The progress in CMOS technology has entered the sub-micron realm, and the technology will approach its limits within about 15 years. Already various novel information processing devices, based on quantum mechanical effects at the nanometer scale, have been widely investigated and some have been successfully demonstrated at the circuit level....

Optoelectronic properties of discotic materials for device applications

Field-effect transistors on tetracene single crystals

We report on the fabrication and electrical characterization of field-effect transistors at the surface of tetracene single crystals. We find that the mobility of these transistors reaches the room-temperature value of 0.4?cm2/V?s. The nonmonotonous temperature dependence of the mobility, its weak gate voltage dependence, as well as the...

Planar nanocontacts with atomically controlled separation

We have developed a technology to reproducibly make gaps with distance control on the single-atom scale. The gold contacts are flat on the nanometer scale and are fabricated on an oxidized aluminum film that serves as a gate. We show that these contacts are clean and can be stabilized via chemical functionalization. Deposition of conjugated...

Carbon nanotube junctions and devices

In this thesis Postma presents transport experiments performed on individual single-wall carbon nanotubes. Carbon nanotubes are molecules entirely made of carbon atoms. The electronic properties are determined by the exact symmetry of the nanotube lattice, resulting in either metallic or semiconducting behaviour. Due to their small diameter,...