Electronic devices usually don’t cope well with extreme heat.
But researchers in Japan have developed a new type of transistor that can operate at temperatures as high as 600°C, or 1,112°F, potentially paving the way for electronics that work in some of the world’s harshest environments.
The research team at Kyoto University created the device using silicon carbide, or SiC, a semiconductor material known for its ability to withstand much higher temperatures and electrical stresses than ordinary silicon.
The findings were published in APL Electronic Devices.
For more than 20 years, researchers have viewed silicon carbide as a promising material for electronics designed for extreme environments.
However, turning that promise into practical electronic circuits has proved difficult.
According to the Kyoto researchers, part of the problem may be that engineers have continued using design ideas originally developed for conventional silicon electronics. Silicon carbide has different properties and may require a different approach.
The team focused on a type of transistor called a junction field-effect transistor, or JFET. Transistors are tiny electronic switches that control the flow of electricity and form the basic building blocks of modern electronic circuits.
Previous silicon carbide JFETs developed by the researchers used a conventional “top-gate” design. However, these devices had difficulty precisely controlling the voltage needed to switch the transistor. They also experienced significant electrical leakage when temperatures became very high. Both problems would make them unsuitable for reliable real-world electronics.
To overcome these limitations, the researchers redesigned the transistor around the natural properties of silicon carbide.
Instead of placing the gate at the top, they created a “bottom-gate” structure. This gave them much better control over the transistor’s threshold voltage, an important factor in determining when the device switches on and off.
The researchers also changed how different parts of the device were electrically isolated. Rather than relying on the semi-insulating silicon carbide substrates used in their earlier designs, they introduced a well-based isolation structure designed to reduce unwanted electrical leakage at high temperatures.
Remarkably, the new design worked on the team’s first attempt.
Tests showed that the transistor continued operating successfully at 600°C. The bottom-gate design significantly improved control of the threshold voltage while dramatically reducing leakage current. The remaining leakage was close to the theoretical minimum expected from the basic properties of silicon carbide itself.
The achievement could eventually help engineers build integrated circuits capable of operating where conventional electronics cannot survive. Such extreme-temperature electronics could potentially be valuable in industrial equipment, energy systems, aerospace technology and other harsh environments where protecting electronics from heat is difficult.
There is still considerable work ahead before the technology can be widely used. The researchers plan to develop more complicated circuits, move toward manufacturing devices across entire semiconductor wafers and ensure that electronic packaging can survive the same extreme conditions.
But demonstrating reliable transistor operation at 600°C represents an important step toward electronics that can keep working even when the heat becomes extraordinary.
