Novel silicon carbide transistors operate at 600°C

Researchers at Kyoto University have developed a new silicon carbide (SiC) junction field-effect transistor (JFET) structure that demonstrates reliable operation at temperatures up to 600°C. Previous research has suggested that complementary JFETs, based on SiC JFETs, can be applied to low-power integrated circuits for operation in extreme environments. However, the JFETs previously developed by researchers — which featured conventional top-gate structures fabricated in semi-insulating SiC substrates — suffered from low controllability and large leakage currents at high temperatures.

The new device uses a bottom-gate architecture to improve the threshold-voltage controllability and a well-based isolation structure to suppress leakage current at high temperatures, thereby addressing the limitations of earlier SiC JFET designs.

“Our goal is to open a new path forward with complementary JFETs designed to harness the intrinsic properties of SiC itself,” said Mitsuaki Kaneko, first author of the research findings published in APL Electronic Devices.

Rather than developing everything from scratch, the team deliberately employed industry-standard manufacturing methods to build their new JFET structure. They also employed well-based isolation instead of a semi-insulating substrate to suppress the high-temperature leakage current.

The result was a new SiC transistor structure that succeeded on the very first attempt. Upon completion of the new design, the team was able to demonstrate that their device can operate successfully at 600°C. The adoption of the bottom-gate structure improved the transistor’s threshold voltage controllability and reduced the leakage current, which is now very close to the theoretical limit predicted from the material properties of SiC.

This study proves that SiC is already a mature power device technology in itself and demonstrates the immense potential of the newly developed bottom-gate structure for implementing reliable, extreme-temperature SiC-based integrated circuits.

However, many challenges still lie ahead on the path to practical implementation. One by one, the team intends to address these by creating more complex circuits, scaling up to wafer-level production and ensuring the entire package remains robust in extreme environments.

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