Battery-like memory withstands extreme heat for future applications

Los Angeles CA (SPX) Dec 10, 2024 - A team of engineers led by the University of Michigan has developed a groundbreaking memory device capable of operating at extreme temperatures, enabling potential use in fusion reactors, jet engines, geothermal wells, and even otherworldly environments.

Unlike standard silicon-based memory, the innovative solid-state device maintains functionality at over 600C, temperatures that surpass the surface heat of Venus and exceed the melting point of lead. This advancement was achieved in collaboration with Sandia National Laboratories.

"It could enable electronic devices that didn't exist for high-temperature applications before," explained Yiyang Li, assistant professor of materials science and engineering at U-M and senior corresponding author of the study, published in *Device*.

Currently, the device can store and rewrite a single bit of information, which aligns with the capability of other high-temperature memory prototypes. However, with additional development, it has the potential to scale up to storing megabytes or gigabytes of data.

Operating at High and Low Temperatures

The memory device relies on heating above 250C to write new information, presenting a challenge for applications requiring lower temperatures. A built-in heater could address this limitation.

What sets this technology apart is its use of oxygen ions rather than electrons for data storage. Traditional silicon-based semiconductors falter above 150C as excessive current flow disrupts memory. In contrast, the oxygen ions in the new device remain stable, moving between two layers-a tantalum oxide semiconductor and a tantalum metal layer-via a solid electrolyte that restricts unwanted charge movements.

A Battery-Like Mechanism

The process mirrors a battery's charge and discharge cycles. A series of platinum electrodes manipulate oxygen ions, toggling the material between states that represent binary data. When oxygen ions leave the tantalum oxide, the material forms a metallic tantalum layer, while the reverse occurs on the other side of the barrier. These changes remain stable until voltage is reversed.

Depending on its oxygen content, tantalum oxide switches between being an insulator and a conductor. Fine-tuning this oxygen gradient could create multiple resistance states, enabling advanced in-memory computing and reducing power consumption.

"In-memory computing chips could help process some of that data before it reaches the AI chips and reduce the device's overall power use," said Alec Talin, senior scientist at Sandia National Laboratories and study co-author.

Advantages and Potential

The device can retain data at temperatures exceeding 600C for over 24 hours. It also offers advantages over alternatives like ferroelectric memory and nanogaps with polycrystalline platinum electrodes, including lower voltage requirements and enhanced analog states for in-memory computing.

Funded by the National Science Foundation, Sandia's Laboratory-Directed Research and Development program, and the University of Michigan College of Engineering, the device was constructed at the Lurie Nanofabrication Facility and examined at the Michigan Center for Materials Characterization.

A patent for this technology has been filed with the U.S. Patent and Trademark Office, and the researchers are seeking partners to commercialize the innovation.

Research Report:Nonvolatile electrochemical memory at 600 + C enabled by composition phase separation