- Published in the prestigious international journal Small Structures (IF: 13.9, Top 7% in JCR) -

Fabrication of ultra-high voltage gallium oxide films through a fusion and hybrid process -

- Expected application as a key fabrication technology for next-generation power semiconductor devices -

Professor Jongmin Oh and student Joonwoo Lee from the Nano Materials and Electronic Devices Laboratory, Department of Electronic Materials Engineering

Professor Jongmin Oh's Research Team from the Department of Electronic Materials Engineering has successfully developed a world-class ultra-high voltage gallium oxide film for power semiconductors, based on interdisciplinary research in nanocomposite synthesis, room-temperature coating processes, device design, and the development of new measurement technologies.

As the importance of high-power applications, such as electric vehicles and renewable energy systems, continues to rise, the power semiconductor industry has been experiencing a rapid annual growth rate. Following SiC and GaN, gallium oxide (Ga₂O₃), which possesses a high breakdown electric field, is now gaining attention as a next-generation power semiconductor material for ensuring high-voltage reliability.

Gallium oxide, with its high theoretical breakdown electric field (~8 MV/cm), has become the subject of intense research recently. While chemical vapor deposition is commonly used to create gallium oxide films due to its ability to produce high-quality films, it has limitations such as long deposition times, the need for extremely high temperatures, and high costs. Moreover, to mitigate electric field concentration effects, complex processes involving multiple steps are often required to fabricate gallium oxide films with intricate structures. However, despite these efforts, previous studies have reported breakdown electric fields of only 2？4 MV/cm, less than 50% of the theoretical value.

The ultra-high voltage gallium oxide film developed by Professor Oh’s team primarily utilizes aerosol deposition, a room-temperature powder impact coating process, and addresses the issue of electric field concentration through optimized nozzle tilting technology. Additionally, by reducing oxygen vacancies and crystallizing the film through post-heat treatment, the team successfully increased the bandgap, one of the key variables for achieving a high breakdown electric field. As a result, a simple-structured gallium oxide film was fabricated, achieving very low leakage current and a breakdown electric field of 5.5 MV/cm―currently the highest reported in the world. https://onlinelibrary.wiley.com/doi/full/10.1002/sstr.202400321

This research was conducted in close collaboration with Professor Sangmo Koo from the Department of Electronic Materials Engineering, Dankook University’s Professor Jongho Won, and Kyung Hee University’s Professor Kanghee Won. The lead author of the paper, Joonwoo Lee, a second-semester master's student in the Department of Electronic Materials Engineering, has already published two SCI(E) papers as the main author, continuing his active research contributions.

Professor Jongmin Oh stated, “Through this research, we have proposed a new deposition mechanism for gallium oxide and demonstrated an ultra-high breakdown electric field. This paves the way for the development of next-generation power semiconductor devices capable of operating reliably at extremely high voltages, and we have high expectations for its application in this field.”

This research was supported by the Basic Research Program of the National Research Foundation of Korea, funded by the Ministry of Science and ICT. The results were published in the prestigious international journal Small Structures (IF: 13.9) on August 21, 2024, under the title "Ultrahigh Breakdown Field in Gallium (III) Oxide Dielectric Structure Fabricated by Novel Aerosol Deposition Method."

Web link : https://onlinelibrary.wiley.com/doi/full/10.1002/sstr.202400321