ElecTrans · Molecular electron transport junctions: spectroscopy of vibrational effects and their controlled manipulation

Molecular electron transport junctions: spectroscopy of vibrational effects and their controlled manipulation

Electron transport through bio-molecular junctions and the influence of electron-phonon interaction on the transport was studied using current-voltage characteristics and inelastic tunneling (IET) spectra. A systematic study of IET phenomena in simple homo-oligopeptides enabled us to identify the vibrational modes that contribute to charge transport in these basic building blocks of proteins. Apart from relatively simple peptides, first steps were undertaken to investigate IET phenomena in a redox protein, Azurin. In a further step, the influence of non-equilibrium vibrational distributions in molecules on charge transport through those molecules was studied. In cooperation with the AMOLF institute in Amsterdam, we exposed our molecular junctions to ultra-short infrared (IR) laser pulses and measured the current change as function of time and excitation energy. We found a correlation of the current response with the organic monolayer, the very first study of this kind. The necessity to have stable electrical contacts to organic monolayers within this project, resulted in the development of a novel approach to molecular electronics on silicon in general. We were able to show that evaporated Pb forms stable and highly reproducible junctions with molecules on Si. Our method is fast, scalable, and compatible with standard semiconductor processing, results in close to 100 % yield, and can help the development of large-scale utilisation of silicon-organic hybrid electronics

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