How researchers created twisted semiconductors for 3D projection

Researchers at the University of Michigan and the Ben-Gurion University of the Negev in Israel teamed up to discover a way to mass-produce spiral semiconductors that can produce 3D images. In the future, this could mean that smartphones and other consumer electronics devices could be capable of producing 3D images.

In 1962, the first realistic 3D images from the University of Michigan were unveiled thanks to the invention of practical holography. The first holographic images were made by creating standing waves of light with bright and dark spots in space, creating an illusion of a material object. This was possible by controlling polarization and phase of light.

Twisting light. Image source: University of Michigan.

Now, the University of Michigan’s semiconductor helices can do the same thing, with photons that pass through and are reflected from and emitted by them. They can be incorporated into other semiconductor devices to vary the polarization, phase, and color of light emitted by the different pixels, which are made from the semiconductor helices.

According to the University of Michigan, until now, making semiconductor spirals with strong twists was difficult because the twisted state isn’t natural to semiconductor materials. Typically, they form sheets or wires. But thanks to nature, the team of chemical engineers figured out a way to guide the attachment of small semiconductor nanoparticles to each other by learning from a proven duo of twisted structures: DNA and proteins.

The video below from the University of Michigan shows how the semiconductor spiral affects the electric field of light traveling through it.

“Amino acids are the quintessential building blocks of proteins,” said post-doctoral research and lead author, Wenchun Feng. “The direction of the spiral of proteins is determined by the geometrical property of amino acids. We found that a common amino acid, cysteine, working together in large numbers can twist not only proteins but also semiconductors.”

Cysteine molecules come in two forms that are exact images of one another, known as a “chiral” molecule.

One unexpected discovery that the team came across was how high the fidelity of this self-assembly process was and how strong the twist of the helices were. Nearly all (98%) of the semiconductor helices had the same twisting direction and behaved like nanoscale fusilli. Some organic molecules can form organic spirals, too, but the light-twisting ability of semiconductor helices proved to be at least five times stronger, and could be varied by electrical field.

When the team let light into the semiconductors, they studied the photons swirling within them. With the help of computer simulations, the team developed design principles and methods for engineering the optical properties of the semiconductor helices for different colors in holography devices.

The study was originally published in the journal Science Advances.