Synthesis, crystal structure and thermal decomposition of [La2(CH3CH2COO)6·(H2O)3]·3.5H2O precursor for high-k La2O3 thin films deposition

Lanthanum acetylacetonate La(C{sub 5}H{sub 7}O{sub 2}){sub 3}.xH{sub 2}O has been used in the preparation of the precursor solution for the deposition of polycrystalline La{sub 2}O{sub 3} thin films on Si(1 1 1) single crystalline substrates. The precursor chemistry of the as-prepared coating solution, precursor powder and precursor single crystal have been investigated by Fourier Transformed Infrared Spectroscopy (FTIR), differential thermal analysis coupled with quadrupole mass spectrometry (TG-DTA-QMS) and X-ray diffraction. The FTIR and X-ray diffraction analyses have revealed the complex nature of the coating solution due to the formation of a lanthanum propionate complex. The La{sub 2}O{sub 3} thin films deposited by spin coating on Si(1 1 1) substrate exhibit good morphological and structural properties. The films heat treated at 800 {sup o}C crystallize in a hexagonal phase with the lattice parameters a = 3,89 A and c = 6.33 A, while at 900 {sup o}C the films contain both the hexagonal and cubic La{sub 2}O{sub 3} phase.