Speaker: Nikolai Zhitenev, Lucent
Date & Time: September 28, 2006 - 11:00am
Location: Room 260, Wright-Rieman Chemistry
Electronic Conducting States in Nano- and Mesoscale Molecular Junctions
Laboratory for Surface Modification
Nikolai Zhitenev, Lucent
11:00am - 12:00noon, Room 260, Wright-Rieman Chemistry
Organic materials can offer new electronic functionality not available in the inorganic devices. However, the integration of organics within nanoscale electronic circuitry poses new challenges for material physics, chemistry and nanofabrication. The electronic properties of devices are determined not solely by the properties of the host materials but are equally dependent on defects that are internal to disordered organic layers, generated at the interfaces and during the device fabrication.
I will discuss three approaches that we use to build small molecular structures. The first group of experiments is targeted toward wiring of a single or just a few molecules. Two other techniques screen the properties of larger molecular junctions with characteristic size of ~50–300 nm but instead allow for experimenting with the topography, the chemical bonding at metal-molecule interface and the defect generation. Surprisingly, the results of all experiments show that the conductance of short molecules is 4–6 orders of magnitude smaller than is commonly believed. The electronic states mediating the transport are the residual defect states that are close in energy to the Fermi level of the contacts rather than the electronic states of the molecules. Finally, I present a new molecular system based on grafted polyelectrolyte layers where the “defects” states determining the transport properties can be controllably created and chemically modified.