Scientists use protons to develop super efficient memory devices

They have produced ultralow power, high-capacity computer chips.
Loukia Papadopoulos
KAUST's ferroelectric neuromorphic computing chip..jpg
KAUST's ferroelectric neuromorphic computing chip.


A KAUST-led international team has found that protons that produce multiple phase transitions in ferroelectric materials could help develop high-performance memory devices, such as brain-inspired or neuromorphic computing chips.

This is according to a press release by the institution published on Sunday.

“Ferroelectrics, such as indium selenide, are intrinsically polarized materials that switch polarity when placed in an electric field, which makes them attractive for creating memory technologies. In addition to requiring low operating voltages, the resulting memory devices display excellent maximum read/write endurance and write speeds, but their storage capacity is low. This is because existing methods can only trigger a few ferroelectric phases, and capturing these phases is experimentally challenging,” said Xin He, who co-led the study under the guidance of Fei Xue and Xixiang Zhang.

The new approach

The new approach conceived by the team is based on the protonation of indium selenide to generate a multitude of ferroelectric phases. It consisted of ferroelectric material deposited in a transistor made of a silicon-supported stacked heterostructure.

“They deposited a multilayered indium selenide film on the heterostructure, which comprised an aluminum oxide insulating sheet sandwiched between a platinum layer at the bottom and porous silica at the top. While the platinum layer served as electrodes for the applied voltage, the porous silica acted as an electrolyte and supplied protons to the ferroelectric film,” noted the statement.

By alternating the applied voltage, the researchers then gradually injected or removed protons from the ferroelectric film. This resulted in several ferroelectric phases with various degrees of protonation, which is crucial for implementing multilevel memory devices with substantial storage capacity.

“Higher positive applied voltages boosted protonation, whereas negative voltages of higher amplitudes depleted protonation levels to a greater extent,” revealed the press release.

“Protonation levels also varied depending on the proximity of the film layer to silica. They reached maximum values in the bottom layer, which was in contact with silica, and decreased in stages to achieve minimum amounts in the top layer.”

The researchers were, however, surprised to find that the proton-induced ferroelectric phases returned to their initial state when the applied voltage was turned off.

 “We observed this unusual phenomenon because protons diffused out of the material and into the silica,” Xue explained.

The team then engineered a film that displayed a smooth and continuous interface with silica resulting in a device that operates below 0.4 volts, a voltage ideal for the development of low-power memory devices. 

“Our biggest challenge was to reduce the operating voltage, but we realized that the proton-injection efficiency over the interface governed operating voltages and could be tuned accordingly,” Xue added.

“We are committed to developing ferroelectric neuromorphic computing chips that consume less energy and operate faster,” Xue concluded in the statement.

Add Interesting Engineering to your Google News feed.
Add Interesting Engineering to your Google News feed.
message circleSHOW COMMENT (1)chevron
Job Board