Fundamental Advance: Multi-Value Logic Transistor Created, Faster Than Binary, Quantum Interface

The image on the left shows two forms of zinc oxide combined to form a composite nanolayer in a new type of transistor: Zinc oxide crystals (inside the red circles) are embedded in amorphous zinc oxide. The image on the right is a computer model of the structure that shows electron density distribution.

 Credit: University of Texas at Dallas

“The concept of multi-value logic transistors is not new, and there have been many attempts to make such devices,” Cho said. “We have done it.”

Through theory, design and simulations, Cho’s group at UT Dallas developed the fundamental physics of a multi-value logic transistor based on zinc oxide. Their collaborators in South Korea successfully fabricated and evaluated the performance of a prototype device.

Cho’s device is capable of two electronically stable and reliable intermediate states between 0 and 1, boosting the number of logic values per transistor from two to three or four.

Cho said the new research is significant not only because the technology is compatible with existing computer-chip configurations, but also because it could bridge a gap between today’s computers and quantum computers, the potential next landmark in computing power.

While a conventional computer uses the precise values of 1s and 0s to make calculations, the fundamental logic units of a quantum computer are more fluid, with values that can exist as a combination of 1s and 0s at the same time or anywhere in between. Although they have yet to be realized commercially, large-scale quantum computers are theorized to be able to store more information and solve certain problems much faster than current computers.

“A device incorporating multi-level logic would be faster than a conventional computer because it would operate with more than just binary logic units. With quantum units, you have continuous values,” Cho said.

“The transistor is a very mature technology, and quantum computers are nowhere close to being commercialized,” he continued. “There is a huge gap. So how do we move from one to the other? We need some kind of evolutionary pathway, a bridging technology between binary and infinite degrees of freedom. Our work is still based on existing device technology, so it is not as revolutionary as quantum computing, but it is evolving toward that direction.”

The technology Cho and his colleagues developed uses a novel configuration of two forms of zinc oxide combined to form a composite nanolayer, which is then incorporated with layers of other materials in a superlattice.
Dr. Kyeongjae Cho, professor of materials science and engineering, and his UT Dallas collaborators developed the fundamental physics of a multi-value logic transistor based on zinc oxide.