Radical nanowires: Has silicon met its match?

U. BUFFALO (US) — Scientists working to identify materials that could one day replace silicon in faster computers may have found one.

In the journal Advanced Functional Materials, a research team reports they have synthesized nanowires made from vanadium oxide and lead.

And these nanowires perform a rare trick: when exposed to an applied voltage near room temperature, the wires transform from insulators that are resistant to carrying electricity to metals that more readily conduct electricity.

Each of these two states—insulator and metal—could stand for a 0 or 1 in the binary code that computers use to encode information, or for the “on” and “off” states that the machines use to make calculations.

Nanowires crafted from vanadium oxide and lead. These wires’ unique electrical properties could make them ideal for use in switching components of computers. View larger. (Credit: Peter Marley)


“The ability to electrically switch these nanomaterials between the on and off state repeatedly and at faster speeds makes them useful for computing,” says study co-author Sambandamurthy Ganapathy, an associate professor of physics at the University at Buffalo.

“Silicon computing technology is running up against some fundamental road blocks, including switching speeds,” adds Sarbajit Banerjee, another co-author and an associate professor of chemistry. “The voltage-induced phase transition in the material we created provides a way to make that switch at a higher speed.”

As with other nanomaterials, the health and environmental impacts of the nanowires would have to be investigated before their widespread use, especially since they contain lead, Banerjee cautioned.

One intriguing characteristic of the material they synthesized is that it only exhibits valuable electrical properties in nano-form. That’s because nanomaterials often have fewer defects than their bulkier counterparts, the researchers explain.

In the case of the lead vanadium oxide nanowires, the wires’ distinctive structure is crucial to their ability to switch from an insulator to a metal.

Specifically, in the insulator phase, the position of the lead in the nanowires’ crystalline structure induces pools of electrons to gather at designated locations. Upon applying a voltage, these pools join together, allowing electricity to flow freely through them all and transforming the material into a metal.

“When materials are grown in bulk, there’s a lot of defects in the crystals, and you don’t see these interesting properties,” says Peter Marley, a PhD student and the study’s lead author. “But when you grow them on a nanoscale, you’re left with a more pristine material.”

The National Science Foundation and the Research Corporation for Science Advancement funded the work.

Source: University at Buffalo