Combustion chemical vapor deposition of CeO2 film

Thin ceria (CeO2) films were deposited onto a-plane sapphire substrates via combustion chemical vapor deposition using toluene as a solvent and Ce(III) 2-ethylhexanoate (Ce-2EH) and tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)(IV) cerium (Ce-(TMHD)(4)) as chemical precursors. Depositions were made at a substrate temperature of 1000 degrees C using several precursor concentrations and aerosol size distributions. Ceria assumes the fluorite (cubic) structure in the polycrystalline films. Films produced with low concentrations (similar to 0.001 M) of Ce-2EH display a preferred orientation in which the (200) axis is perpendicular to sapphire substrates. Similar low concentration of Ce-(TMHD)(4) yield films with (111) preferred orientation. High precursor concentrations (>0.002 M) and/or large aerosol size distributions yielded films containing ceria clusters that appear to have nucleated in the gas phase and adhered to the substrates in addition to material that nucleated on the substrates. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.