Papers by Author: Shizuo Fujita

Abstract: Applying a bicolor coherent treatment of a Nd-YAG laser with wavelength 1.32 μm and its second harmonic generation, we have investigated photoinduced SHG in Au nanoparticledeposited ZnO nanocrystallinne (NC) films. We have established that coexistence of the such crystallites gives substantially better results compared to the pure ZnO NC deposited onto the glass substrate. It was shown that the value of the second order susceptibility obtained for the large incident angles of the fundamental and writing beams is equal to about 23 pm/V. The better results are obtained during the phototreatment at temperatures near the 60 oC for the Au doped samples and is almost non-sensitive to temperature for the pure samples. The further increase of the temperature leads to decay of the optical second harmonic generation

Abstract: ZnO nanowalls and nanocolumns were synthesized on Si3N4 (50 nm)/Si (001) substrates at low growth temperature (350 and 400 oC) by metalorganic chemical vapor deposition (MOCVD) with no metal catalysts. ZnO nanowalls with extremely small wall thicknesses below 10 nm and nanocolumns with diameters over 100 nm were formed on the Si3N4/Si substrates relying on MOCVD-growth temperature. It was found that ZnO nanowalls have a strong c-axis preferred orientation with a hexagonal structure, while ZnO nanocolumns have a weak c-axis preferred orientation with broken stacking orders in synchrotron x-ray scattering experiments. In addition, strong free-exciton emission from the ZnO nanowalls was clearly observed in photoluminescence measurements. On the other hand, we could not observe any emission bands from the ZnO nanocolumn samples.