Ultra-low-loss Diamond Power Device Development

At Kanazawa University, Professor Norio Tokuda, who specialises in research, and fellow researchers are pushing the performance boundaries of current silicon-based power devices. Tokuda notes that to achieve Japan's ambitious national goals for carbon neutral industry and energy supply, plus automation to resolve many social issues such as care for an ageing population; high-performance power devices are vital. Tokuda says: 'The performance of silicon-based devices is thought to be nearing the maximum possible, therefore much research is being devoted to a range of exotic materials, including diamond.' He explains: 'Diamond is considered to be the ultimate material for power devices. It offers the highest-known dielectric breakdown field and carrier mobility as well as high thermal conductivity and the possibility of extreme miniaturisation.' Despite these properties, it has proven hard to fabricate an effective MOSFET based on diamond, not least owing to diamond's hardness and chemical stability. Tokuda says: 'We were the first to create atomically-step-free and hydroxyl-terminated diamond surfaces that enabled us to demonstrate a working diamond metal oxide semiconductor field effect transistor (MOSFET) with inversion channel in 2016. Since then, we have been working to refine this concept and to create other diamond-based electronic/quantum devices.'