● Overview ●

     We are conducting consistent research on next generation solar cells, hetero-superlattices, and diamond-based materials from thin film creation to device prototyping.  We use laser and plasma technologies to fabricate thin films while adhering to our basic principle, which is to use ecologically friendly elements.

 i) Solar cells based on an ecological semiconductor, iron silicide

Iron silicide is a direct gap semiconductor, which has a bandgap of 0.85 eV and an absorption coefficient a hundred times larger than Si.  It can be used to create solar cells, which save resources and lower environmental loads.

 ii) Basic spintronics studies using Fe-Si ferromagnetic/semiconducting heterostructures

We are searching for novel device designs that integrate optical, electronic, and magnetic principles by combining Fe-Si ferromagnets (B2, DO₃-Fe₃Si) and semiconductors (β-FeSi₂, nanocrystalline FeSi₂).  These devices have contributions from d-electrons to the electric conduction and are operable at room temperature.

 iii) Low-temperature heteroepitaxial growth of diamond single crystal thin films

Besides being a jewel, diamond is also an excellent material from the viewpoint of industrial applications.  Although chemical vapor deposition is a mainstream fabrication technique, we use physical vapor deposition to conduct research from a completely different aspect.  Our target is to lower the growth temperature and to achieve heteroepitaxial growth on heterogeneous substrates.

 iv) Creation and application of ultrananocrystalline diamonds (UNCD)

We were the first to successfully create UNCD using physical vapor deposition.  Thus, pure UNCD with little residual amorphous carbon can be obtained.  We have been measuring and analyzing the basic material properties in order to achieve various applications, ranging from hard coatings to heat sinks and semiconductors.