Researchers at the Institute of Industrial Science (IIS) at the University of Tokyo in Japan have built tiny transistors that do not use silicon. Instead, the team doped gallium into indium oxide and then crystallized it to make a material that supports the movement of electrons.
Transistors are everywhere. From the smartphone to smart homes, cars to airplanes, transistors are an integral part of modern-day electronics. Made out of silicon, transistors have helped hasten the development of newer technologies but are also now lagging behind.
Computers that once filled the room now fit in the palm of the hand, thanks to silicon-based transistors. However, as we seek to minimize the size of electronics further, we have started to see the limitations of silicon as well. Squeezing out more from silicon-based transistors in smaller configurations is getting harder by the day, and this is where researchers are looking for new alternatives.
Improvements over standard gates
While seeking transistors that can be further miniaturized, the researchers at IIS were also looking for ways to improve upon the transistor design further. The gate of the transistor decides whether it remains on or off.
The researchers wanted to design a gate which surrounds the channel, where the current flows. “By wrapping the gate entirely around the channel, we can enhance efficiency and scalability compared with traditional gates,” explained Anlan Chen, researcher at IIS, who was involved with the work.
By dumping silicon in their design, the researchers also dumped its limitations. But indium oxide had to be improved in certain aspects to make it work with electricity more favorably. So, the research team set up to dope it with gallium.
Silicon-based transistors have hit a wall when it comes to shrinking their size. Alternates are the need of the hour. Image credit: SweetbunFactory/iStock
How was the transistor made?
Indium oxide is known to carry oxygen-vacancy defects, which lead to defects in the device and reduce its stability. The doping with gallium addresses these oxygen vacancies and can improve the transistors’ reliability. However, this needs to be carefully done.
The team used atomic-layer deposition to coat the channel region with a thin film of gallium-doped indium oxide (InGaOx), one layer at a time. Once the deposition was complete, the film was heated to form a crystalline structure that supports electron mobility.
The research team successfully developed a metal oxide-based field-effect transistor (MOSFET) with a gate-all-around design. “Our gate-all-around MOSFET, containing a gallium-doped indium oxide layer, achieves high mobility of 44.5 cm2/Vs,” added Chen in the press release.
“Crucially, the device demonstrates promising reliability by operating stably under applied stress for nearly three hours.”
The researchers also reported that their MOSFET outperformed other devices that have previously been developed. It paves the way for the development of reliable, high-density electronic components. These are likely to have applications in futuristic areas such as artificial intelligence or processing big data.
By further shrinking the size of transistors, the researchers also showed that next-gen technology will likely be accompanied with a further shrinking in size of devices. More importantly, it also showcased that research into material design could yield solutions that look beyond silicon for future applications.
The research findings were shared at the 2025 Symposium on VLSI Technology and Circuits.
AloJapan.com