Harnessing Phase Separation: A Game Changer for AI Memory Tech
Newly discovered role of phase separation can help develop memory devices for energy-efficient AI computing.
Researchers have unveiled that phase separation, alongside oxygen diffusion, crucially supports the long-term retention of information in memristors, specifically in resistive random access memory (RRAM). This discovery challenges previous models that suggested limited retention capabilities, highlighting potential applications in energy-efficient AI and rad-hard memory chips for space exploration.
Memristor Memory
Phase separation, when molecules part like oil and water, works alongside oxygen diffusion to help memristors—electrical components that store information using electrical resistance—retain information even after the power is shut off, according to a University of Michigan-led study recently published in the scientific journal Matter.
Up to this point, explanations have not fully grasped how memristors retain information without a power source, known as nonvolatile memory, because models and experiments do not match up.
Investigating Long-Term Data Retention
“While experiments have shown devices can retain information for over 10 years, the models used in the community show that information can only be retained for a few hours,” said Jingxian Li, U-M doctoral graduate of materials science and engineering and first author of the study.
To better understand the underlying phenomenon driving nonvolatile memristor memory, the researchers focused on a device known as resistive random access memory or RRAM, an alternative to the volatile RAM used in classical computing, and are particularly promising for energy-efficient artificial intelligence applications.
Discovering the Role of Phase Separation
The specific RRAM studied, a filament-type valence change memory (VCM), sandwiches an insulating tantalum oxide layer between two platinum electrodes. When a certain voltage is applied to the platinum electrodes, a conductive filament forms a tantalum ion bridge passing through the insulator to the electrodes, which allows electricity to flow, putting the cell in a low resistance state representing a “1” in binary code. If a different voltage is applied, the filament is dissolved as returning oxygen atoms react with the tantalum ions, “rusting” the conductive bridge and returning to a high resistance state, representing a binary code of “0.”
It was once thought that RRAM retains information over time because oxygen is too slow to diffuse back. However, a series of experiments revealed that previous models have neglected the role of phase separation.
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