| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 91 === The growth characteristics of one dimensional nc-Si/SiOx composite nanowires using SiCl4/H2 as well as oxygen absorbed on chamber wall in a hot-filament chemical vapor deposition reactor were investigated in this study. The composite nanowires were grown on various substrates by non-VLS mechanism at lower substrate temperatures in comparison with polycrystalline film formed at high temperature. Structural and compositional characterizations of the nanowires by TEM and electron energy-loss spectroscopy (EELS) indicate that dendritic self-assembly of Si nanorods are embedded in the amorphous SiOx nanowires. PL analyses of the nc-Si/SiOx composite nanowires show a blue-green light emission at room temperature.
Aligned rutlie and anatase TiO2 nanorods as well as anatase TiO2 nanowalls have been synthesized using a template- and catalyst-free CVD method. Formation of various crystal phases and morphologies of TiO2 nanostructures were dependent on the substrate temperatures as well as the distances between the Ti source and the substrates. Anatase films, nanowalls and well-aligned nanorods were formed at substrate temperatures of 420~485℃, 500~535℃ and 560~605℃, respectively. Rutile nanorods were grown at substrate temperatures of 630~655℃ in a longer distance between Ti source and substrate. TEM analyses indicate that rutile and anatase TiO2 nanorods were both single crystalline. Optical characterizations of the TiO2 nanostructures show that the bandgap of anatase and rutile phase were 3.2 as well as 3.0 eV, respectively.
|
|---|
