Preparation of anatase TiO2 thin films with ((OPr)-Pr-i)(2)Ti(CH3COCHCONEt2)(2) precursor by MOCVD

Abstract

The reaction of titanium tetraisopropoxide, with 2 equiv of N,N-diethyl acetoacetamide affords Ti((OPr)-Pr-i)(2)(CH3COCHCONEt2)(2) (1) as colorless crystals in 80% yield. Compound 1 is characterized by spectroscopic (Mass and H-1/C-13 NMR) and microanalytical data. Molecular structure of 1 has been determined by a single crystal X-ray diffraction study, which reveals that it is a monomeric, cis-diisopropoxide and contains a six coordinate Ti(IV) atom with a cis(CONEt2), trans(COCH3) configuration (1a) in a distorted octahedral environment. Variable-temperature H-1 NMR spectra of 1 indicate that it exists as an equilibrium mixture of cis, trans (1a) and cis, cis (1b) isomers in a 0.57: 0.43 ratio at -20 degreesC in toluene-d(8) solution. Thermal properties of 1 as a MOCVD precursor for titanium dioxide films have been evaluated by thermal gravimetric analysis and vapor pressure measurement. Thin films of pure anatase titanium dioxide (after annealing above 500 degreesC under oxygen) have been grown on Si(100) with precursor 1 in the substrate temperature range of 350500 degreesC using a bubbler-based MOCVD method.