| Abstract
| - Yttria-stabilized zirconia (YSZ) films were synthesized by atomic layer deposition (ALD). Tetrakis(dimethylamido)zirconium and tris(methylcyclopentadienyl)yttrium were used as ALD precursors withdistilled water as oxidant. From X-ray photoelectron spectroscopy (XPS) compositional analysis, theyttria content was identified to increase proportionally to the pulse ratio of Y/Zr. Accordingly, the targetstoichiometry ZrO2/Y2O3 = 0.92:0.08 was achieved. Crystal and grain structures of ALD YSZ filmsgrown on amorphous Si3N4 were analyzed by X-ray diffraction (XRD) and atomic force microscopy(AFM). The microstructure of the polycrystalline films consisted of grains of tens of nanometers indiameter. To evaluate ALD YSZ films as oxide ion conductor, freestanding 60 nm films were preparedwith porous platinum electrodes on both sides of the electrolyte. This structure served as a solid oxidefuel cell designed to operate at low temperatures. Maximum power densities of 28 mW/cm2, 66 mW/cm2, and 270 mW/cm2 were observed at 265 °C, 300 °C, and 350 °C, respectively. The high performanceof thin film ALD electrolyte fuel cells is related to low electrolyte resistance and fast electrode kinetics.The exchange current density at the electrode−electrolyte interface was approximately 4 orders ofmagnitude higher compared to reference Pt-YSZ values.
- Low electrolyte resistance and high exchange current densities of nanoscale yttria-stabilized zirconia electrolytes prepared by atomic layer deposition can lead to power densities of solid oxide fuel cells in excess of 200 mW/cm2 at temperatures below 400 °C.
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