Surrey student’s discovery could improve smart electronics

Undergraduate student Lea Motte studied a new device for her final-year project, the multimodal transistor. An alternative to conventional thin-film transistors, which are often used in smartwatches and solar panels, the multimodal transistor was invented and developed by Surrey PhD candidate Eva Bestelink and supervisor Dr Radu Sporea.

Motte used a defining feature of multimodal transistors, the separation of controls for introducing electrons into the device and allowing them to move across the transistor. 

Through computer simulations, she found that choosing the right voltage to apply to the transport control region could prevent unwanted hot-carrier effects. Additionally, it ensured that the current through the transistor remained constant in a range of operating conditions.

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PhD student Eva Bestelink studied the discovery in a paper published in Advanced Electronic Materials. Bestelink confirmed the behaviour in multimodal transistors with measurements in microcrystalline silicon transistors and device simulations to understand the device physics that underpin its ability.

It is hoped that future technologies that use multimodal transistors could be more power-efficient, and could lead to high-performance amplifiers which are essential for measuring signals from environmental and biological sensors.

“We now have a better understanding of what the multimodal transistor can offer when made with materials that cause numerous challenges to regular devices,” said Bestelink. “For circuit designers, this work offers insight into how to operate the device for optimum performance. In the long-term, the multimodal transistor offers an alternative for emerging high-performance materials where traditional solutions are no longer applicable.”

Dr Radu Sporea, senior lecturer in semiconductor devices at Surrey, said that the discovery shows the value of multidisciplinary collaboration through close interactions with one of Surrey’s partner institutions in Rennes, France. 

“It demonstrates again that in our team, everyone’s contribution can lead to important developments, even as undergraduates,” Sporea said. “This is why, at Surrey, we encourage our students to explore widely and to challenge the boundaries of their assigned projects.”