VO2 is said to act like an insulator at room temperature, while behaving like a conductor at temperatures of more than 68°C. It is this characteristic, known as metal-insulator transition, that is being explored in an EU Horizon 2020 project called Phase-Change Switch.
Following a challenging selection process, EPFL has been chosen to coordinate the project, which has been granted €3.9million of EU funding. The potential for this new technology has attracted a range of interested parties.
Although the electronic properties of VO2 have been known for a while, scientists have been unable to explain them until now.
The atomic structure of VO2 is said to change as the temperature rises, transitioning from a crystalline structure at room temperature, to a metallic one at temperatures of more than 68°C, which occurs within less than 1ns.
"VO2 is also sensitive to other factors that could cause it to change phases, such as by injecting electrical power, optically, or by applying a THz radiation pulse," said professor Adrian Ionescu, from EPFL.
Unlocking VO2’s full potential has proved tricky because its transition temperature of 68°C is too low for modern electronic devices. However, two EPFL researchers have found the addition of germanium to VO2 film can lift the material's phase change temperature to more than 100°C.
For the first time, scientists claim they can make ultra-compact, modulable frequency filters. The technology also uses VO2 and phase-change switches and, according to the team, is particularly effective in the frequency range crucial for space communication systems (the Ka band, with programmable frequency modulation between 28.2 and 35GHz).
The hope is that these discoveries will spur further research into applications for VO2 in ultra-low-power electronic devices.
In addition to space communications, the team are also looking at other fields such as, neuromorphic computing and high-frequency radars for self-driving cars.
