Published online by Cambridge University Press: 03 March 2011
The growth morphology and interface structure of Nd1.85Ce0.15CuO4−y (NCCO) films grown by pulsed laser deposition on two different types of substrates, “perovskite” LaAlO3 (LAO) and SrTiO3 (STO) and “fluorite” Y2O3-stabilized ZrO2 (YSZ), were studied using cross-sectional electron microscopy. Structurally, the NCCO films are different when grown on the two types of substrates in three aspects: (i) epitaxy, (ii) substrate-film intermixing, and (iii) substrate-film interface roughness. In general, films deposited on “fluorite” substrates showed better superconducting properties than the films grown on “perovskite” substrates, especially for thinner films. Lattice mismatch considerations are not sufficient to explain the observed differences since films grown on the YSZ substrate showed sharp substrate-film interface in spite of their large lattice misfit. The atomic arrangements at the interface were analyzed in terms of electrostatic energy (charge balance) and matching of the oxygen sublattices in order to account for the experimental results.