| Research Abstract |
Our accomplishments are classified into 2 groups : (1)Clarification and prediction of phenomena in materials that are important in current technology, and (2)prediction of new properties and functions of nano-materials that may constitute basis of future technology. In the first group, the followings are clarified :
1.Diffusion mechanisms of Boron impurities in SiO2 : B takes the several charge states in SiO2, and it is clarified that diffusion pathways and corresponding activation energies are sensitive to the charge state.
2.Si nano-crystal is forged by femto-second laser irradiation of SiO2.Difference in diffusion coefficients of the 2 elements allows the formation of the Si crystal below the melting temperature
3.The energy gap of InN is found to be less than 1 eV, thus opening the possibility of nitride semiconductors with a wide range of wavelengths in optoelectronic devices.
4.ZrB2 is shown to be a good substrate for GaN good-quality films.
In the second group, we have found the followings :
1.Hydrogen-covered Si becomes a nanoscale magnet by removing H atoms in a controlled way and hereby forming nanoscale dangling-bond networks
2.Carbon nanotubes with zigzag edges exhibit a variety of magnetic properties depending on their tube radii
3.Semiconducting carbon nanotubes become metallic when 2 different tubes become a double-wall nanotube, depending on the ratio of the radii of the two tubes.
4.In tubes and fullerenes, internal space plays a crucial role in determining electronic structures near Fermi level.
5.In Al atom wires, the conductance occasionally increases upon stretching the wire. This is characteristic to atom wires consisting of sp-orbital elements.
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