Self-assembled nanowires can help make transistors smaller and faster

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Washington, April 21 (ANI): A team of scientists at the University of Illinois (U. of I.), US, has found a new way to make transistors smaller and faster, by using self-assembled, self-aligned, and defect-free nanowire channels made of gallium arsenide.

Nanowires are attractive building blocks for both electronics and photonics applications.

Compound semiconductor nanowires, such as gallium arsenide, are especially desirable because of their better transport properties and versatile heterojunctions.

However, a number of challenges - including integration with existing microelectronics - must first be overcome.

"Our new planar growth process creates self-aligned, defect-free gallium-arsenide nanowires that could readily be scaled up for manufacturing purposes," said U. of I. electrical and computer engineering professor Xiuling Li

"It's a non-lithographic process that can precisely control the nanowire dimension and orientation, yet is compatible with existing circuit design and fabrication technology," Li added.

The gallium-arsenide nanowire channel used in the researchers' demonstration transistor was grown by metal organic chemical vapor deposition using gold as a catalyst.

The rest of the transistor was made with conventional microfabrication techniques.

While the diameter of the transistor's nanowire channel was approximately 200 nanometers, nanowires with diameters as small as 5 nanometers can be made with the gold-catalyzed growth technique, the researchers report.

The self-aligned orientation of the nanowires is determined by the crystal structure of the substrate and certain growth parameters.

In the current work, the researchers grew the gallium-arsenide nanowire channel in place, instead of transferring it.

In contrast to the common types of non-planar gallium arsenide nanowires, the researchers' planar nanowire was free from twin defects, which are rotational defects in the crystal structure that decrease the mobility of the charge carriers.

"By replacing the standard channel in a metal-semiconductor field-effect transistor with one of our planar nanowires, we demonstrated that the defect-free nanowire's electron mobility was indeed as high as the corresponding bulk value," said U. of I. graduate research assistant Seth Fortuna.

"The high electron mobility nanowire channel could lead to smaller, better and faster devices," he added.

Considering their planar, self-aligned and transferable nature, the nanowire channels could help create higher performance transistors for next-generation integrated circuit applications, according to Li.

The high quality planar nanowires can also be used in nano-injection lasers for use in optical communications. (ANI)

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