Electrical conductivity of thin film ceria grown by pulsed laser deposition

Gd-doped ceria (GDC) thin films, 0.5-1.8 mu m thick, were deposited on Pt and sapphire substrates by pulsed laser deposition (PLD) method. The in-plane and the perpendicular-to-plane conductivities (hereafter, "across-plane" conductivity) of thin films were measured and compared to that of bulk sample. X-ray diffraction and electron microscopy results showed that the films on Pt and sapphire were polycrystalline cubic with a columnar structure. The grain conductivities of the GDC films, obtained from the impedance spectra of in-plane and across-plane measurements, were slightly lower than that of the GDC bulk. However, very little difference in conductivity was shown between films, regardless of substrates and measurement modes. The activation energies and the Po-2 dependence of the GDC thin films were similar to that of bulk GDC. In the low temperature range, the GDC films exhibited conductivities about one order of magnitude higher than that of the YSZ (Yttria-stabilized zirconia) film. (c) 2007 Elsevier Ltd. All rights reserved.