Memristor Capable of Three Stable Resistive States Could Challenge Flash Memory

Development makes it possible to encode information that is not based on binary logic

Illustration: ETH Zurich/American Chemistry Society

The imminent demise of flash memory at the hands of some new technological upstart has been predicted at least for the last decade.  The latest pretender to the throne is the so-called memristor (also called resistive RAM, ReRAM, or RRAM).  Of course, if you don’t like the term “memristor”, you can alternatively refer to it as “two-terminal non-volatile memory devices based on resistance switching.”

Now researchers at ETH Zurich have designed a memristor device out of perovskite just 5 nanometres thick that has three stable resistive states, which means it can encode data as 0,1 and 2, or a “trit” as opposed to a “bit.”

The research, which was published in the journal ACS Nano, developed model devices that have two competing nonvolatile resistive switching processes. These switching processes can be alternatively triggered by the effective switching voltage and time applied to the device.

"Our component could therefore also be useful for a new type of IT (Information Technology) that is not based on binary logic, but on a logic that provides for information located 'between' the 0 and 1," said Jennifer Rupp, professor in the Department of Materials at ETH Zurich, in a press release. "This has interesting implications for what is referred to as fuzzy logic, which seeks to incorporate a form of uncertainty into the processing of digital information. You could describe it as less rigid computing."

The researchers also believe this capability could make these devices applicable to so-called neuromorphic computing.  Earlier this year, researchers at Northwestern University used the two-dimensional material molybdenum disulfide (MoS2) to create the third terminal for the memristor to simulate the neurons of the human brain.

While artificial intelligence is an attractive offshoot of this research, the main achievement has been to identify the carriers of electrical charge and understand their relationship with the three stable states.

Rupp added: "This is extremely important knowledge for materials science which will be useful in refining the way the storage operates and in improving its efficiency."

The Semiconductors Newsletter

Monthly newsletter about how new materials, designs, and processes drive the chip industry.

About the Nanoclast blog

IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.