Esmaspäeval, 3. juunil 2013. kell 16.15 toimub FI peahoone, Riia 142, 2. korruse fuajees
Väike materjalifüüsika ja spektroskoopia seminar nr. 158
Timo Tolmusk: TÜ LOTE füüsika eriala 3. kursuse üliõpilane, LSL, FI
Laser treatment and spectroscopic studies of TiO2 thin films
TiO2 õhukeste kilede lasertöötlus ja spektroskoopilised uuringud
The aim of this work was to introduce the laser treatment of optical materials to achieve light-induced local modification of structural and luminescence properties. Two experimental setups for laser treatment of thin films were assembled and the impact of a UV continuous wave (CW) and pulsed laser treatment of TiO2 thin films doped with rare earth impurities (Sm3+) were characterized by Raman and fluorescence microspectroscopy.
The initially amorphous rare earth doped TiO2 materials were prepared by using sol-gel spin-coating technique. It was found with Raman study that a conventional heat treatment leads to the formation of either anatase or brookite phase of TiO2, depending on the heat treatments applied between successive coatings. Some samples were shown to develop crystalline structure and intense photoluminescence when point irradiation with 364 nm CW laser at power densities ~6×105 W/cm2 were applied for a few seconds. Pulsed laser treatment of larger areas at 266 nm demonstrated phase transition from initial amorphous phase to anatase phase and then to rutile phase. (Juhendaja Valter Kiisk)