Normal memory chips couldn't withstand the hellscape of Venus so scientists have crafted something that can
Heat is no friend of any kind of memory chip. That will be no surprise for PC gamers with our wealth of cooling systems and heat sink options—unfortunately, those solutions aren't suitable for every data retention situation. As such, a research team has developed a chip that will keep working throughout extreme temperature conditions.
A US team based at USC Viterbi School of Engineering in Southern California has created a graphene tungsten memristor that can reliably operate at outlandishly high temperatures. Per the team's paper in the journal Science, 'interfacial engineering' allowed for this memristor to operate "reliably up to 700 °C with an ON/OFF current ratio >103, data retention >50 hours and endurance >109 switching cycles" (via The Brighter Side).
As even the most hard-wearing silicon-based SSDs tend to fail at 200 °C, and the surface of Venus easily breaches 400 °C, you can understand the scientific demand for memory that can deal with the heat. The kicker is that the team set out to make something completely different with graphene.
“To be honest, [the discovery was made] by accident, as most discoveries are," One of the paper's authors, Joshua Yang, explained, “If you can predict it, it’s usually not surprising, and probably not significant enough.”
The USC team has built a memristor out of a tungsten-hafnium oxide-graphene stack. Both tungsten and graphene can withstand extreme heat as it is, and the hafnium oxide completes the sandwich as a switching layer between the two electrode slices.
You may remember that in 2024, researchers at the University of Pennsylvania had previously created flash memory based on an aluminium scandium nitride ferroelectric diode that can withstand up to 600 °C.
Similar devices that feature platinum instead of graphene in their 'bottom layer' degrade quickly in similar tests, as tungsten atoms make a break for it at high temperatures. As tungsten atoms pool in the platinum layer, the device becomes no longer able to 'switch' between resistive states, and essentially stops functioning as viable memory.
Swap out the platinum electrode for graphene, though, and those tungsten atoms don't get anywhere near as clingy at high temperatures.
The graphene-based memristor proved exceptionally hardy over time, holding on to both ON/OFF memory states for 145 hours on average across 30 different devices at high heat. During the 700 °C tests specifically, these memristors underwent 1 billion switching cycles, pulsing around 1.5 volts every 30 nanoseconds.
With how expensive it is to get anything into space, hardy memory that can switch quickly at relatively low voltages is definitely good news.
But it's not just space missions that could benefit, with memristors especially appealing to AI workloads as they can perform matrix multiplication directly through the flow of current. “Over 92 percent of the computing in AI systems like ChatGPT is nothing but matrix multiplication,” Yang explains, “This type of device can perform that in the most efficient way, orders of magnitude faster and at lower energy.”