New process yields improved molecular electronics

A simple, chemical way to attach electrical contacts to molecular-scale electronic components has been developed by researchers at the US National Institute of Standards and Technology.

A simple, chemical way to attach electrical contacts to molecular-scale electronic components has been developed by researchers at the National Institute of Standards and Technology (NIST).

The recently patented method, detailed <link>here=http://patapsco.nist.gov/TS/220/sharedpatent/pdf/6828581.pdf</link>, attaches a layer of copper on the ends of delicate molecular components to avoid damage to the components that commonly occurs with conventional techniques.

Molecular electronics – designing carbon-based molecules to act as wires, diodes, transistors and other microelectronic devices – is said to be one of the most dynamic frontiers in nanotechnology.

A key challenge in molecular electronics is making electrical contacts to the fragile molecules, chemical chains that are easily damaged. Currently, this is most often done by vaporising a metal onto the molecules that stand like blades of grass on a metal substrate.

The vaporised metal atoms are supposed to settle on the tops of the molecules but they also often eat away at the delicate structures, or fall through gaps in the “turf” and short out the device. Yields of working devices are typically only a few percent.

NIST researchers designed a technique in which the molecules are synthesised with an additional chemical group attached to the top of the molecule.

The chip is immersed in a solution including copper ions, which preferentially bind to the added group, forming a strong, chemically bonded contact that also protects the underlying molecule during further metallic vapour deposition steps.

Tests at NIST have demonstrated that the technique works well on surfaces patterned with microcontact printing, producing clean, sharply defined edges that are important for the fabrication of practical devices.

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