Memristor pushed to ‘new levels of performance’

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Scientists at the University of Southampton say they have pushed the memristor to a new level of performance after experimenting with its component materials. The work is said to hold the potential for a new generation of electronic devices.

The memristor was first postulated in a paper published in 1971 by Professor Leon Chua, who argued that it should be regarded as the fourth fundamental circuit element, along with the resistor, capacitor and inductor. But it wasn’t until 2008 that researchers from HP Labs proved its existence. According to Prof Chua, memristors should be able to remember how much charge has passed through them.

The Southampton team has demonstrated a memristor technology that can store up to 128 discernible memory states per switch – almost four times more than previously reported. This was accomplished by evaluating several configurations of functional oxide materials.

Professor Themis Prodromakis said: “This is a really exciting discovery, with potentially enormous implications for modern electronics. Memristors are a key enabling technology for next-generation chips, which need to be highly reconfigurable yet affordable, scalable and energy-efficient."

In a paper published in Scientific Reports, the team said it developed a series of two terminal prototype metal-insulator-metal (MIM) ReRAM cells, with TiO2 as a solid electrolyte. Seven interface barrier layer configurations were studied: TiO2 only; AlxOy/TiO2; TaxOy/TiO2; SiO2/TiO2; ZnO/TiO2; HfOx/TiO2; and WOx/TiO2. Active layer thickness was maintained at 4nm, while the barrier and TiO2 layers were 40nm thick.

Prof Prodromakis added: “We are thrilled to be working with world-leading industry, bringing innovations into new electronic systems that require bespoke customisation.

“At the same time this technology is ideal for developing novel hardware that can learn and adapt autonomously, much like the human brain.”