Characterization of atomic layer deposited and sputtered yttria-stabilized-zirconia thin films for low-temperature solid oxide fuel cells

Electrolyte thin films of yttria-stabilized- zirconia (YSZ) for low temperature solid oxide fuel cell applications are investigated. Films of same thickness and composition are fabricated by using two distinct thin film deposition techniques, atomic layer deposition (ALD) and radio frequency (RF) sputtering. Scanning electron microscopic images indicate that both methods form uniform, polycrystalline films on amorphous matrix. Deposition rates of ALD and sputtered YSZ electrolyte films are easily controllable. In-plane ionic conductivity of O²⁻ ions for YSZ is measured using electrochemical impedance spectroscopy. Experimental results show that, at a low temperature of 250°C, ALD YSZ thin films exhibit considerably lower resistance to the conduction of oxygen ions as compared to the sputtered films. This lower resistance results in better ionic conductivity of ALD YSZ thin films.