Chemical Vapor Deposition And Raman Analysis Of TiO2 Nanocrystals

• Main Authors: Chia-Wen Liang, 梁嘉文
• Other Authors: Dah-Shyang Tsai
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/15945053853178371660

碩士 === 國立臺灣科技大學 === 化學工程系 === 96 === In this thesis, TiO2 nanorods have been grown on the substrates of F-doped tin oxide (FTO) conducting glass and sapphire (SA) (100) using chemical vapor deposition (CVD). Through adjusting the growth parameters of CVD, we may obtain nanorods of rutile, anatase, and mixed phases, which are further examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), raman scattering, and photoluminescence (PL). TiO2 nanorods of rutile structure grown on FTO are influenced by the preferred orientation of underlying tin oxide, which is also of rutile structure. They both exhibit the preferential crystal plane (301). TiO2 nanorods of rutile structure grown on SA(100) display single (002) diffraction peak, indicating the crystals grow in [001] direction. TiO2 nanorods of anatase structure grown on FTO display no preferred orientation, while a preferential crystal plane of (220) on SA(100). Fitting the raman scattering signal of rutile TiO2 with modified spatial correlation (MSC) model results in the length of phonon confinement, which is consistent with the disk like crystal observed in the SEM micrograph. We also observe the A1g line broadening with the decreasing crystal size, and the red shift in A1g line position due to residual stresses and phonon confinement. Analysis of PL spectra of TiO2 nanorods indicates a weak contribution in UV emission due to the lattices of rutile, anatase, and the mixed phase. They exhibit strong green emissions at wavelength 503, 515, 511 nm because of the surface oxygen vacancies.