Condensed-Matter Physics & Materials Science Seminar

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