Faculty
Noboru Ohtani
Major research fields
Wide Bandgap Semiconductors, Crystallographic Defects
Solving the problem of climate change is a great challenge before us, and energy conservation combined with a more efficient use of electricity can mitigate the problem since it is the most widely used energy source at home and in industry. Hence, power electronics is now expected to play a vital role in the global energy conservation scenario. Present-day Si power electronics, however, suffer from performance limitations due to their material properties. Wide band gap semiconductor silicon carbide (SiC) is a possible solution to this problem and has attracted considerable attention in recent years. In our laboratories, we pursue research topics related to semiconductor SiC together with several industrial partners. Our current research focuses on crystal growth and defect physics in SiC crystals with a view to improving the quality of the crystal. The research topics include studies of the following: the formation mechanisms of structural defects in hexagonal SiC; the growth surface morphology of SiC crystals; and the influence of structural and surface defects on electrical properties of SiC.
Major relevant publications
- T. Takahashi, C. Ohshige, N. Ohtani, M. Katsuno, T. Fujimoto, S. Sato, H. Tsuge, T. Yano, H. Matsuhata and M. Kitabatake, "Structural and electrical characterization of the initial stage of physical vapor transport growth of 4H-SiC crystals," Materials Science Forum 821-823, 90 (2015).
- C. Ohshige, T. Takahashi, N. Ohtani, M. Katsuno, T. Fujimoto, S. Sato, H. Tsuge, T. Yano, H. Matsuhata and M. Kitabatake, " Defect formation during the initial stage of physical vapor transport growth of 4H-SiC in the [11-20] direction," Journal of Crystal Growth 408, 1 (2014).
- N. Ohtani, C. Ohshige, M. Katsuno, T. Fujimoto, S. Sato, H. Tsuge, W. Ohashi, T. Yano, H. Matsuhata and M. Kitabatake, "Structural investigation of the seeding process for physical vapor transport growth of 4H-SiC single crystals," Journal of Crystal Growth 386, 9 (2014).
- T. Fujimoto, N. Ohtani, T. Tsuge, M. Katsuno, S. Sato, M. Nakabayashi and T. Yano, "A Thermodynamic Mechanism for PVT Growth Phenomena of SiC Single Crystals," ECS Journal of Solid State Science and Technology 2, N3018 (2013).
- N. Ohtani, S. Ushio, T. Kaneko, T. Aigo, M. Katsuno, T. Fujimoto and W. Ohashi, "Tunneling Atomic Force Microscopy Studies on Surface Growth Pits due to Dislocations in 4H-SiC Epitaxial Layers," Journal of Electronic Materials 41, 2193 (2012).