How Nanowires Got Their Groove Back
REHOVOT, Israel, Aug. 25, 2011 — As nanowires grow vertically, they can become unruly and lose their full potential as effective semiconductors. Now, a team from Weizmann Institute of Science has found a way to grow semiconducting nanowires out, not up, on a surface, producing long, orderly, aligned structures. And because semiconductors with controlled structures are at the core of the most advanced technologies, this breakthrough could enable the production of semiconductor nanostructures with enhanced electronic and optical properties, suitable for applications including LEDs, lasers, information storage media, transistors, computers, photovoltaics and more.
Illustration of nanowires growing along nanogrooves. (Images: Weizmann Institute of Science)
Using a method that usually produces vertical nanowires with excellent optical and electronic properties, the Weizmann team grew nanowires made of gallium nitride (GaN), which become unruly only once they are harvested and assembled into arrays. To bypass this problem, they used sapphire as a base, but rather than growing the nanowires on a smooth surface, they deliberately cut various surface patterns, such as steps and V-shaped grooves, along different planes of the sapphire crystal.
As a result, the steps and grooves provided a strong guiding effect, coaxing the nanowires to grow horizontally along the edges or within the grooves — producing well-aligned, millimeter-long nanowire arrays.
Although it is still not fully clear how a method that normally produces vertical nanowires works to create horizontal growth, the team managed to combine, in a single step, the synthesis and assembly of well-structured nanowires with unique properties suitable for a wide range of applications, simply by “getting them into the groove.”
For more information, visit: www.weizmann.ac.il
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