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-heptanedio nato)(IV) cerium (Ce-(TMHD)(4)) as chemical precursors. Depositions were ma de at a substrate temperature of 1000 degrees C using several precursor con centrations and aerosol size distributions. Ceria assumes the fluorite (cub ic) structure in the polycrystalline films. Films produced with low concent rations (similar to 0.001 M) of Ce-2EH display a preferred orientation in w hich the (200) axis is perpendicular to sapphire substrates. Similar low co ncentration of Ce-(TMHD)(4) yield films with (111) preferred orientation. H igh precursor concentrations (>0.002 M) and/or large aerosol size distribut ions 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 ri ghts reserved.