A new low-temperature, catalyst-free technique for growing copper nanowires could serve as interconnects in electronic device fabrication and as electron emitters in a television-like, very thin flat-panel display known as a field-emission display.
“We can grow forests of freestanding copper nanowires of controlled diameter and length, suitable for integration into electronic devices,” said Kyekyoon Kim, a professor of electrical and computer engineering at the University of Illinois.
“The copper nanowires are grown on a variety of surfaces, including glass, metal, and plastic by chemical vapor deposition from a precursor,” said Hyungsoo Choi, a research professor in the Micro and Nanotechnology Laboratory and in the department of electrical and computer engineering. “The patented growth process is compatible with contemporary silicon-processing protocols.”
Typically, researchers grow the nanowires of 70 to 250 nanometers in diameter on a silicon substrate at temperatures of 200 to 300°C and require no seed or catalyst. Processing conditions, such as substrate, substrate temperature, deposition time, and precursor feeding rate control the size of the nanowires. The columnar, five-sided nanowires terminate in sharp, pentagonal tips that facilitate electron emission.
To demonstrate the practicability of the low-temperature growth process, the researchers first grew an array of copper nanowires on a patterned silicon substrate. Then they fashioned a field-emission display based on the array’s bundles of nanowires.
In a field-emission display, electrons emitted from the nanowire tips strike a phosphor coating to produce an image. Because the researchers used a bundle of nanowires for each pixel in their display, the failure of a few nanowires will not ruin the device.
“The emission characteristics of the copper nanowires in our proof-of-principle field-emission display were very good,” said Kim, who also is affiliated with Illinois’ department of materials science and engineering, department of bioengineering, department of nuclear, plasma and radiological engineering, Beckman Institute, Micro and Nanotechnology Laboratory, and the Institute for Genomic Biology. “Our experimental results suggest bundled nanowires could lead to longer lasting field-emission displays.”
Source: 1 May 2008, In Tech Home, Growing copper nanowires for electronic devices, Staff at Tech Home, All contents copyright of ISA © 1995-2008 All rights reserved.