Effect of Rate on Pulsed Laser Deposition of Yttria Stabilized Zirconia Electrolyte Thin Films for SOFCs

Abstract

Yttriastabilized zirconia (YSZ) thin films were deposited by pulsed laser deposition (PLD) at laser repetition frequencies of 10–50 Hz. Controlling the laser repetition frequency can achieve high deposition rate of YSZ, but high deposition rate at high laser repetition frequency can adversely affect the crystallinity of the resulting film. In the present work, Xray diffraction (XRD) of YSZ thin films deposited at 10–50 Hz unexpectedly indicated no significant differences. Wellcrystallized YSZ thin films were obtained for all laser repetition frequencies. This result may be due to a sufficient substrate temperature of 1000 K during processing. The oxideion conductivity of each thin film was comparable to that of bulk YSZ. Only minor differences in Y2O3 content, residual stress, grain size, and grainboundary width were observed among the films. We concluded that similar quality YSZ thin films were obtained at all deposition frequencies. Oxideion conductivity was affected by the temperature at which the substrate was deposited. The YSZ thin films deposited at 900 K and 1000 K showed similar oxideion conductivity and films deposited at 800 K showed lower oxideion conductivity. This difference could perhaps be due to narrow grainboundary width. The YSZ thin film with highest oxideion conductivity was fabricated at an intermediate substrate temperature of 900 K with a deposition rate of 86 nmآ·min−1 at 50 Hz, without additional hightemperature annealing greater than 1273 K. The YSZ growth rates were faster than the rates for other gasphase methods such as midfrequency and DC sputtering.