More efficient and reliable SiC devices for a greener future

Osaka, Japan - Researchers at The University of Osaka have developed a novel technique to enhance the performance and reliability of silicon carbide (SiC) metal-oxide-semiconductor (MOS) devices, a key component in power electronics. This breakthrough utilizes a unique two-step annealing process involving diluted hydrogen, to eliminate unnecessary impurities and significantly improve device reliability.

SiC power devices offer superior energy efficiency compared to traditional silicon-based devices, making them ideal for applications like electric vehicles and renewable energy systems. However, previous attempts to improve SiC MOS device performance relied on introducing impurities like nitrogen, which unfortunately compromised reliability and limited operating voltage range. This necessitated strict gate drive design, hindering wider adoption.

The University of Osaka team discovered that a two-step high-temperature hydrogen annealing process, performed before and after gate oxide deposition, could drastically improve both performance and reliability without the need for these problematic impurities. This process effectively removes defects at the oxide/SiC interface, resulting in a lower interface state density and higher channel mobility. The devices demonstrated improved immunity against both positive and negative bias stress, expanding their operational voltage range.

This breakthrough has significant implications for the future of power electronics. By enhancing the reliability and performance of SiC MOS devices, this technique paves the way for their wider adoption and contributes towards a more energy-efficient future.  This will be particularly beneficial in applications requiring high power and switching frequencies, such as electric vehicle inverters and renewable energy converters.

"SiC MOS devices, despite being in mass production, haven't yet reached their full potential in terms of performance and reliability," explains Prof. Takuma Kobayashi, the lead researcher. "Our findings offer a solution to this long-standing challenge and open up exciting new possibilities for SiC power devices. We overcame many hurdles during this research, and I'm grateful to all my co-authors for their contributions."

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The article, “Performance and reliability improvements in SiC(0001) MOS devices via two-step annealing in H₂/Ar gas mixtures,” will be published in Applied Physics Express at DOI: https://doi.org/10.35848/1882-0786/adf6ff

About The University of Osaka

The University of Osaka was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world. Now, The University of Osaka is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.

Website: https://resou.osaka-u.ac.jp/en