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Researchers Discover New Structure Inside Nanowires

In the corners of hexagonal nanowires researchers discover a new space for electrons and holes

2 min read
Researchers Discover New Structure Inside Nanowires
Howard Jackson, the University of Cincinnati

Nanowires made from III-V semiconductors like indium gallium arsenide are having a bit of run of late. Yesterday, I reported on a new method for growing them on graphene.

Now researchers at the University of Cincinnati have discovered that a newly developed architecture for semiconductor nanowires has a hidden nook in which to find electrons and holes. The discovery opens up a new understanding of the fundamental physics of nanowires.

The research, which was published in the journal Nano Letters (“Optical, Structural, and Numerical Investigations of GaAs/AlGaAs Core–Multishell Nanowire Quantum Well Tubes”), involved a host of characterization and measurement techniques.

University of Cincinnati physics professors Howard Jackson and Leigh Smith, who together led the research, believe that applications of this new structure could range from solar cells to environmental sensors.

“This kind of structure in the gallium arsenide/aluminum gallium arsenide system had not been achieved before,” Jackson said in a press release. “It’s new in terms of where you find the electrons and holes, and spatially it’s a new structure.”

The researchers grew a quantum well tube around the inner core of the nanowire. With this new architecture, they discovered that electrons were distributed in an unusual way around the facets of the hexagonal nanowire.

“Having the faceting really matters. It changes the ballgame,” Jackson said in the release. “Adjusting the quantum well tube width allows you to control the energy—which would have been expected—but in addition we have found that there’s a highly localized ground state at the corners which then can give rise to true quantum nanowires.”

The nanowires reportedly have a high quantum efficiency that means they should have a very high electrical sensitivity to light, making them potentially ideal for photovoltaic applications.

While the researchers believe that the impact of these nanowires may still be somewhat far off, based on the preliminary stage of this line of research, they think it should present a new paradigm for understanding the fundamental physics surrounding nanowires.

Photo: Howard Jackson, the University of Cincinnati

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3D-Stacked CMOS Takes Moore’s Law to New Heights

When transistors can’t get any smaller, the only direction is up

10 min read
An image of stacked squares with yellow flat bars through them.
Emily Cooper

Perhaps the most far-reaching technological achievement over the last 50 years has been the steady march toward ever smaller transistors, fitting them more tightly together, and reducing their power consumption. And yet, ever since the two of us started our careers at Intel more than 20 years ago, we’ve been hearing the alarms that the descent into the infinitesimal was about to end. Yet year after year, brilliant new innovations continue to propel the semiconductor industry further.

Along this journey, we engineers had to change the transistor’s architecture as we continued to scale down area and power consumption while boosting performance. The “planar” transistor designs that took us through the last half of the 20th century gave way to 3D fin-shaped devices by the first half of the 2010s. Now, these too have an end date in sight, with a new gate-all-around (GAA) structure rolling into production soon. But we have to look even further ahead because our ability to scale down even this new transistor architecture, which we call RibbonFET, has its limits.

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