Thin film growth and microstructure analysis of CeO2 prepared by MOCVD

CeO2 thin films were prepared by metal-organic chemical vapor deposition (MOCVD) using tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)cerium(iv), [Ce(thd)(4)], as the precursor. The films were grown in a horizontal cold-wall reactor at low pressure and temperatures of 400-900 degrees C in an atmosphere of argon/oxygen. SrTiO3, yttria stabilized zirconia (YSZ), and MgO were used as substrates. Films were prepared on single crystalline substrates with a (100) orientation as well as on polycrystalline YSZ. The film microstructure was investigated by X-ray diffraction and the surface morphology was studied by scanning electron microscopy (SEM). The growth rate was determined using data obtained by profilometry and cross-section SEM. The films are polycrystalline with a (100) preferential orientation with respect to the substrate orientation. Low oxygen partial pressures deteriorated the crystalline quality. The SEM images of the surface and the cross sections demonstrated a columnar microstructure. The growth rates in the range of 25-250 nm/h were strongly dependent on the precursor feeding rate but less affected by the deposition temperature and substrate material.