Growth of nanocrystalline TiO2 films by MOCVD using a novel precursor

Thin films of TiO2 have been deposited on glass substrates by metalorganic chemical vapour deposition (MOCVD) using a novel, volatile, stable, oxo-β-ketoesterate complex of titanium, viz., bis(ethyl-3-oxo-butanoato)oxotitanium(IV) [TiO(etob)2]2. The complex was prepared through a straightforward synthesis. Various spectroscopic techniques have been used to confirm its structure. Thermogravimetric analysis has been carried out to study the thermal properties of the complex. Films of TiO2 were grown from the complex by low-pressure MOCVD at temperatures ranging from 400 to 525 °C. These films were characterized for their morphology by transmission electron microscopy, scanning electron microscopy, and atomic force microscopy and by electron diffraction for their crystallinity. All the films grown in this temperature range are very smooth. Films grown above 480 °C consist of nearly monodisperse, nanocrystals of the anatase phase. Spectrophotometry shows the bandgap to be in the range 3.4-3.7 eV for films grown at different temperatures. It was observed that the bandgap increases with the decrease in the growth temperature, confirming the nanocrystalline nature of the TiO2 films.