Current-voltage measurements of metal-molecule-metal tunnel junctions formed from p-conjugated thiols exhibit an inflection point on a plot of ln(I/V2) against 1/V, consistent with a transition in tunneling barrier shape from trapezoidal to triangular. The position of this inflection point was found to scale linearly with the offset in energy between the Au Fermi level and the highest occupied molecular orbital as determined by ultraviolet photoelectron spectroscopy. Asymmetric voltage drops at the two metal-molecule interfaces lead to a bias polarity dependence of the barrier transition.
Citation: Physical Review Letters
Issue: No 2
Pub Type: Journals
charge transport, molecular electronics, nanotechnology, self-assembled monolayers