RAMAN SCATTERING AND OPTICAL STUDIES OF Fe DOPED TiO2 FILMS

Abstract: Anatase and rutile forms of TiO2 and their Fe doped (5 at %) films have been made successfully using a simple spin coating metalorganic decomposition method. The Raman spectra show the characteristic modes of either Anatase or rutile TiO2. Fe-doped TiO2 films shows a paramagnetic behaviour both at 5 K and at room temperature. Recently, there has been a great deal of interest in finding room temperature ferromagnetism in transparent transition metal doped TiO2, ZnO and other materials so called diluted magnetic semi-conductors (DMS) [1]. Theoretical calculations show that ferromagnetism is stable in DMS based on wide bandgap semiconductor. Hence, significant efforts have been made to grow these oxide DMS films. In the present work, we have used metalorganic decomposition (MOD), a versatile and a low cost spin coating method, for the fabrication of TiO2 anatase and rutile forms. Rutile TiO2 is tetragonal with a = 0.459 nm and c = 0.296 nm, and an optical bandgap of 3 eV while the anatase TiO2 is also tetragonal with a = 0.378 nm and c = 0.952 nm with a bandgap of 3.2 eV. Iron substituted TiO2 films were prepared on sapphire substrates using MOD spin coating method. Separate solutions were made using different concentrations of Ti-ethylhexoxide, and Fe-ethylhexanoate precursor solutions. Films (thickness ~1µm) were prepared by dispensing th