"We believe that reproducible electrical measurements of molecular electronic devices will speed the entry-to-market of this promising emerging technology," Curt Richter of NIST told nanotechweb.org. "These measurements will also help lead to a fundamental understanding of how charges are transported in molecules."
To make a test structure, the researchers sandwiched a monolayer of eicosanoic acid molecules between a series of perpendicular aluminium wires. The resulting alumina (AlOx) tunnel-junction-based crossbar device exhibited hysteretic switching behaviour. Richter and colleagues believe this is the result of an interaction between the molecules and the wire electrodes.
The scientists also tested crossbar structures without a layer of eicosanoic acid molecules to ensure that the electrical results were due to the presence of the molecular monolayer and not the test structure.
According to Richter, the fact that the devices' current-voltage (IV) curves and two-state behaviour were reproducibly measured in two independent laboratories indicates that the effect is not a measurement artefact. It also shows that the devices are robust enough to ship via conventional methods and remain active.
"Molecular electronics is such a fast-moving and technically challenging field that this is the first independent experimental confirmation of the electrical performance of molecular-monolayer-based devices that we are aware of," said Richter. "In addition to IV measurements, NIST researchers took what we believe are the first capacitance-voltage [CV] curves of molecular-monolayer-based devices." The capacitance loop also showed two-state behaviour.
The scientists reported their work at the Government Microcircuit Applications and Critical Technology Conference (GOMACTECH) 2003 held in the US last week.