New Silicon Carbide Transistor Operates at 600°C, Paving the Way for Venus Probes

Japanese researchers have developed a silicon carbide transistor that can operate at temperatures as high as 1,112°F (600°C). The breakthrough could help engineers build electronics for extreme environments, including future probes designed to explore the surface of Venus, where temperatures can reach approximately 860°F (460°C) beneath the planet’s dense carbon dioxide atmosphere.

Transistors are essential components in modern electronics because they regulate the flow of electrical current. The new device is a type of junction field-effect transistor, or JFET. Unlike conventional transistors, a JFET controls conductivity by using an electric field to regulate the current flowing through a semiconductor channel.

JFETs are commonly used in specialized electronics because they are more difficult to miniaturize than metal-oxide-semiconductor field-effect transistors, or MOSFETs. MOSFETs dominate consumer devices such as smartphones and computers. However, JFETs can produce lower electrical noise because they do not depend on oxide layers that may introduce interference.

The Kyoto University research team described the new high-temperature transistor in a study published Aug. 17 in APL Electronic Devices. The research focuses on a silicon carbide, or SiC, JFET designed to maintain stable performance in temperatures above 600°C.

Why Venus electronics need extreme heat resistance

Silicon carbide JFETs have been considered promising candidates for Venus missions for decades because SiC can withstand significantly higher temperatures than conventional silicon. Venus landers, however, have historically survived on the planet for only a short time. The Soviet-era Venera 13 mission holds the record, transmitting data for approximately 2 hours and 7 minutes after landing.

“Silicon-based electronics have limited flight times in past landers to just a few hours,” the researchers noted. Electronics made with silicon carbide could extend the operating life of spacecraft exposed to the high temperatures and pressures found on Venus.

SiC integrated circuits could also support other demanding applications, including deep-space exploration, geothermal drilling, aerospace engine controls and industrial systems that operate where traditional silicon electronics cannot function reliably.

Despite their potential, earlier SiC JFETs faced two major limitations: poor control over the switching voltage and excessive leakage current. These problems are linked to the way the silicon carbide substrate is doped. Doping adds carefully selected atoms to the semiconductor to change its electrical properties and create the transistor’s gate and current-carrying channel.

In a semiconductor with a regular crystal structure, dopant atoms can spread farther into the material than intended. At high temperatures, this can change the voltage needed to activate the transistor channel, making the device harder to control. Earlier SiC JFET designs could experience threshold-voltage shifts of more than 2 volts.

Leakage current creates another problem. Above approximately 660°F (350°C), the electrical resistance of silicon carbide decreases. As a result, current may continue flowing even when the transistor is switched off. This can cause incorrect signals, reduce efficiency and increase power consumption.

Even the most advanced earlier JFETs were generally limited to long-term operation around 930°F (500°C). The Kyoto University team believed that solving the problem would require a transistor architecture designed specifically for silicon carbide rather than adapting concepts originally developed for silicon electronics.

“We believe that the lack of progress is due to the research community trying to apply silicon-era ideas to fundamentally different materials,” said lead author Mitsuaki Kaneko, an associate professor in Kyoto University’s Faculty of Engineering.

A bottom-gate design improves transistor stability

To improve the device’s performance, the researchers developed a silicon carbide JFET with a bottom-gate structure. In this configuration, the gate is positioned beneath the conductive channel instead of using a conventional arrangement.

The gate region was heavily doped to keep its electrical profile stable. This design reduces the effect of dopant atoms moving deeper into the silicon carbide and helps prevent large changes in the threshold voltage as the temperature rises.

The team also formed two semiconductor regions, known as wells, around the transistor channel. The boundaries between these wells act as barriers that block unwanted current. As a result, even when the silicon carbide becomes more conductive at high temperatures, current is prevented from bypassing the channel while the transistor is switched off.

The researchers tested how effectively the new JFET switched electrical current on and off. They also compared the measured threshold voltage with the theoretical value predicted from the device’s thickness and doping profile. Testing was performed from room temperature to approximately 1,110°F (600°C).

The prototype maintained stable transistor operation at temperatures above 873 kelvin, or approximately 1,110°F (600°C). The bottom-gate design also kept the threshold-voltage error below 0.1 volt at around 752°F (400°C), demonstrating significantly improved control at elevated temperatures.

The technology could eventually be used inside jet engines and gas turbines, where electronic sensors and controls must function close to extreme heat sources. Today, many components are protected with heat shields, long cables and energy-intensive cooling systems. Electronics that can operate directly at high temperatures could simplify these systems and enable new engine designs.

More testing is needed before the transistor can be used in spacecraft or aircraft. The researchers must integrate the device into more complex circuits, scale production to wafer level and verify that complete electronic packages can withstand extreme temperatures, pressure and long operating periods.

Previous NASA research has shown that integrated circuits using SiC JFETs can withstand temperatures of approximately 860°F (460°C) and pressures of 9.3 megapascals for 60 days. Other SiC circuits have operated for more than a year in air at approximately 930°F (500°C). In 2024, researchers in Japan also developed a diamond-based MOSFET capable of operating at temperatures of at least 570°F (300°C).