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As devices shrink in size and grow in complexity, we need to find ways of building electronics to meet these demands and use less energy in doing so.
Recently, the idea of using functional oxides in nanoelectronic circuits has been growing. Functional oxides can be made to rapidly switch from an insulating state to a conducting state by a range of external stimuli.
The EU-funded PHASE-CHANGE SWITCH project is putting the unique properties of one of these materials – vanadium dioxide (VO2) – to use in replacing silicon-based switches and adding voltage-controlled reconfigurable functions to today’s electronics.
Their work is showing that VO2 could outperform silicon and revolutionise the way we build electronic devices, making them simpler and more energy efficient. The project’s discoveries could have applications in space communications, neuromorphic computing, and high-frequency radars for autonomous cars.
Abundant and non-toxic, VO2 acts as an insulator below 68 °C and behaves like a metal at higher temperatures – changing atomic structure in less than a nanosecond. As with other functional oxides, this switching of properties can also be induced by electrical current, light, and high-frequency signals.
‘By adding a small amount of germanium to vanadium dioxide, we have been able to push the transition temperature up to around 90 °C, the temperature at which many electronic chips or radars operate. This opens up a huge field of applications in radio-frequency communications and neuromorphic computation,’ says project coordinator Adrian Ionescu of École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland.
‘As well as creating a new kind of material, we are redesigning electronic functions to make use of it – achieving better performance with simpler and lower-cost technology.’
Aerospace applications
PHASE-CHANGE SWITCH researchers have produced three novel types of components that make use of the unique properties of VO2.
The so-called ‘steep slope’ chips and circuits based on VO2 offer new functionality and need less energy input than current devices.
The team has also designed circuits that produce an oscillating electronic signal. Many devices use oscillators. The novel VO2-based version can process electrical signals in a way which mimics the behaviour of neurons, leading to applications in designing artificial neural systems.
The third main arm of the team’s efforts has been in developing ultra-compact and energy-efficient radio-frequency devices that can be tuned to filter radio signals. Especially effective in the frequency range used for aerospace communications, these novel devices could have a large number of uses in this field.
In their efforts to deliver the next generation of small, ultra-low-power electronic devices, the team hopes to make energy savings of at least 10 times compared to current technology in IoT communications and node processing.
Detecting airborne SARS-CoV-2?
‘An unexpected turn was discovering that VO2 can be used to build extraordinary tuneable terahertz sensors for extremely small biological objects,’ says Ionescu. ‘We are currently trying to patent such a sensor to detect specific viruses in the air – including coronavirus.’
‘Currently, our partner Thales is evaluating the technology’s capability for use in airborne, medium power and radio-frequency applications, while IBM is exploring the potential of the project’s findings for neuromorphic computing,’ he adds.