The Incredible Shrinking Component
A research group at Ohio State led by engineering Professor Nitin Padture is performing pioneering work on nanoscale oxide materials that will eventually lead to better computer memories and chemical sensors.
Padture, who is the College of Engineering Distinguished Professor in the Department of Materials Science and Engineering, says his work on integrating nanowires into electronics started with an epiphany he had some years ago while shopping at Radio Shack for electronic components for his son’s science project.
“At that time, nanowire research was the rage, where researchers were studying oxide nanowire ‘components’ laid across gaps in electrical contact pads on substrates,” says Padture, who is also the founding director of the Center for Emergent Materials, an NSF-funded Materials Research Science and Engineering Center, at Ohio State. “The trouble was that the electrical contacts with the nanowires, where the entire length of the nanowire was acting as a ‘component,’ were unreliable, leading to erroneous results. Also, the nanowires, while ‘nano’ in diameter, were really ‘micro’ in length.”
Oxide materials have been used in electronics for a long time because these materials possess some unique sets of properties. For example, some oxides can be used to store memory in computer chips, cell phones and iPods. Other oxides serve as actuators; they have what are called “active” properties, where their shape changes precisely in response to an applied electric field. Or oxides may be used in sensors, because the electrical resistance of an oxide changes dramatically when exposed to trace amounts of harmful chemicals or gases.
When the size of the oxide materials shrinks to nanoscale — several thousandths of the diameter of a human hair — many of these interesting properties become more pronounced, or completely new properties start to emerge. Also, nanoscale oxides occupy very little precious real estate in a device, so they can be packed more densely, and they consume less power. In this realm of nanotechnology, Padture and his colleagues find solutions to computing and sensing challenges.
Back in his laboratory, Padture and his research team synthesized “heterojunction” nanowires with a nickel oxide (NiO) segment as the active memory component, which is intimately connected to gold (Au) nanowire leads that can be reliably connected to a power source or other nanowires. This unique geometry makes the oxide segment truly nanoscale in all directions, and its intimate bonding with the gold nanowire at the “heterojunction” solves the contact problem.
This discovery is allowing fundamental size-effect studies of the nanoscale oxide materials for the first time.
Padture’s research group has pioneered and perfected the synthesis of such high-definition nanowires in a wide variety of oxides (NiO, TiO2, SnO2, BaTiO3, PbTiO3), materials that can serve as computer memories, gas sensors or actuators.
“The ultimate goal,” says Padture, “is to self-assemble these nanowires into densely-packed, multifunctional integrated circuits, the holy grail of nanoelectronics.”
Contact:
Nitin Padture, (614) 247-8114, padture.1@osu.edu
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