CLEVELAND A research team at Case Western Reserve University has found that gold catalysts shaped in the form of a cube, triangle, or other higher order structures grow nanowires about twice as fast and twice as long compared to wires grown with the more typical spherically-shaped catalysts.
This finding could prove useful to other scientists who are growing nanowires to build sensors fast enough to detect changes in red and white blood cells. These sensors in turn could help identify various forms of cancer in the body. The wires are so small as small as one-5,000th the width of a human hair - they could also be used to build the next generation of "invisible" computer chips.
Xuan Gao, assistant professor of physics, and R. Mohan Sankaran, associate professor of chemical engineering, describe their work in the paper, "Shape-Controlled Au Particles for InAs Nanowire Growth," published in the journal Nano Letters.
Their research team included Case Western Reserve graduate students Pin Ann Lin and Dong Liang and Hathaway Brown Upper School student Samantha Reeves.
The researchers tested growth using both the preferentially-shaped and spherical catalysts under identical conditions to rule out error in the comparisons.
They suggest that the long accepted model of vapor-liquid-solid, or VLS, growth is incomplete, and that more tests are needed in order to fully understand the process.
Here's why: the researchers found that that the nanowires grown with the triangular catalyst have a much thicker layer of the metal Indium than the VLS nanowire growth model predicts.
The finding suggests a correlation between Indium concentration and growth enhancement.
The team made the discovery when they beamed electrons at the nanowires to release high energy x-rays, a process called energy-dispersive X-ray spectroscopy. The magnitude of these energy bursts were used to determine chemical properties of the n
|Contact: Kevin Mayhood|
Case Western Reserve University