Nanowires crafted from vanadium oxide and lead. These wires’ unique electrical properties could make them ideal for use in switching components of computers. Image: Peter Marley, with colored added.

Few
modern materials have achieved the fame of silicon, a key element of computer
chips and the namesake for Silicon Valley, home to some of the world’s most
prominent technology firms.

The
next generation of computers, however, may not rely so much on silicon.

University
at Buffalo (UB) researchers are among scientists working to identify materials
that could one day replace silicon to make computing faster. Their latest find:
A vanadium oxide bronze whose unusual electrical properties could increase the
speed at which information is transferred and stored.

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

The
reason that these nanowires are so special is that they 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.

“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, a UB associate professors of physics.

“Silicon
computing technology is running up against some fundamental road blocks, including
switching speeds,” adds Sarbajit Banerjee, another co-author and a UB
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.

When exposed to an applied voltage near room temperature, these nanowires transform from electrical insulators to electrical conductors. Each wire is about 180 nm wide. Image: Peter Marley, with color added.

Banerjee
and Ganapathy oversaw the study, which appeared online in Advanced Functional Materials. UB chemistry graduate student Peter
Marley was lead author. Other contributors include Peihong Zhang, a UB associate
professor of physics, and students from Ganapathy’s research group.

One
intriguing characteristic of the material they synthesized is that it only
exhibits valuable electrical properties in nanoform. That’s because
nanomaterials often have fewer defects than their bulkier counterparts,
Banerjee and Marley 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,” Marley says. “But when you
grow them on a nanoscale, you’re left with a more pristine material.”

Source: University at Buffalo