New transistor operates 8.5 times faster for AI applications

Researchers from the Tokyo University of Science and Japan’s National Institute for Materials Science (NIMS) have reportedly developed the fastest electric-double-layer transistor using an ion conductive ceramic thin film and a diamond thin film. The transistor may be used to develop energy-efficient, high-speed edge devices with a range of applications, including future event prediction and pattern recognition in images (including facial recognition), voices and odours.

An electric-double-layer transistor works as a switch using electrical resistance changes caused by the charge and discharge of an electric double layer formed at the interface between the electrolyte and semiconductor. Because this transistor is able to mimic the electrical response of human cerebral neurons (acting as a neuromorphic transistor), its use in AI devices is promising. However, existing electric-double-layer transistors are slow in switching between on and off states, with the transition time ranging from several hundreds of microseconds to 10 milliseconds.

The researchers developed their electric-double-layer transistor by depositing ceramic (yttria-stabilised porous zirconia thin film) and diamond thin films with a high degree of precision using a pulsed laser, forming an electric double layer at the ceramic–diamond interface. The zirconia thin film is able to absorb large amounts of water into its nanopores and allow hydrogen ions from the water to migrate through it, enabling the electric double layer to be rapidly charged and discharged. This enables the transistor to operate quickly.

The researchers measured the speed at which the transistor operates by applying pulsed voltage to it and found that it operates 8.5 times faster than existing electric-double-layer transistors. The team also confirmed the ability of this transistor to convert input waveforms into different output waveforms with precision — a requirement for transistors to be compatible with neuromorphic AI devices.

The project produced a new ceramic thin film technology capable of rapidly charging and discharging an electric double layer several nanometres in thickness. This is a notable achievement in the effort to create high-speed, energy-efficient AI-assisted devices. These devices, in combination with various sensors (such as smart watches, surveillance cameras and audio sensors), are expected to offer useful tools in a range of industries. The research findings were published in Materials Today Advances.

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