Laboratories are able to create millions of carbon nanotubes--but manipulating them into useful positions has been a stumbling block for realizing the dream of smaller, more efficient electronic and photonic devices. But a new discovery by a team of researchers at the University of Nebraska-Lincoln (Lincoln, NE) may enable a solution, and with little or no manipulation necessary. The research was featured on the cover story of Nanotechnology.
Using a process based on optical near-field effects, professor Yongfeng Lu, postdoctoral researcher Yunshen Zhou, and their team in UNL's Laser Assisted Nano-Engineering Lab created nanoscale devices based on connecting sharp-tipped electrodes with individually self-aligned carbon nanotubes.
Previous efforts in this area by other research groups tried to use advanced instrumentation to manipulate carbon nanotubes after growth. But Lu said that approach is only good for research purposes because it's time consuming and expensive.
"With our method, there's no requirement for expensive instrumentation and no requirement for tedious processes. It's a one-step process," he said. "We call it 'self-aligning growth.' The carbon nanotubes 'know' where to start growth.
"In previous efforts, they could only manipulate carbon nanotubes one piece at a time, so they had to align the carbon nanotubes one by one. For our approach using optical near-field effects, all locations with sharp tips can accommodate carbon nanotube growth. That means we can make multiple carbon nanotubes at a time and all of them will be self-aligned."
While the UNL team has not yet been able to produce large numbers self-aligned carbon nanotubes, Lu and his team see potential for significant expansion that could lead to new applications in devices such as biosensors, light emitters, photon sensors, tiny molecular motors and memory cells.
"We have shown that we can use optical near-field effects to control growth for a small amount of carbon nanotubes," said Lu, Lott professor of electrical engineering at UNL. "We want to make this process scalable so it can be used to make large numbers at a time so we can make a circuit or a system by this approach."
For more information see the paper, Self-aligned growth of single-walled carbon nanotubes using optical near-field effects, in Nanotechnology.
