Molecular electronic devices closer to reality

Researchers at Northwestern University, led by Mark Hersam, assistant professor of materials science and engineering, have become the first to measure a unique and versatile nanoelectric effect - called resonant tunnelling - through individual molecules mounted directly on silicon.

The findings were published online Nov. 1 by Nano Letters, a publication of the American Chemical Society. The article will appear on the cover of the journal's January 2004 issue. "This work represents the first experimental realisation of a molecular resonant tunnelling device on a semiconductor," said Hersam. "The device works at room temperature and on silicon, which are important features that suggest that it can be made compatible with conventional silicon microelectronics. It's easier to make inroads if you complement current technology rather than replace it."

Silicon microelectronics has undergone relentless miniaturisation during the past 30 years leading to dramatic improvements in computational capacity and speed. At the most fundamental limit, individual molecules have been envisaged as functional electronic devices. When interfaced with conventional circuitry, resonant tunnelling devices allow improved efficiency and reduced power consumption in computer architectures.

Resonant tunnelling also may allow individual molecules to be detected and identified, thus creating future opportunities for high sensitivity sensors.