High-Performance TiO2/ZrO2/TiO2 Thin Film Capacitor by Plasma-Assisted Atomic Layer Annealing.

Although laminate structures are widely used in electrostatic capacitors, unavoidable heterogeneous interfaces often deteriorate the dielectric properties by impeding film crystallization. In this study, a TiO2/ZrO2/TiO2 (TZT) laminate structure, where upper-TiO2 deposited on the heterogeneous interface was crystallized by plasma-assisted atomic layer annealing (ALA), was investigated. ALA effectively induced the phase transition of the upper-TiO2 from the amorphous or anatase phase to the rutile phase, leading to an increase in the dielectric constant, whereas the ZrO2 blocking interlayer maintained the amorphous phase owing to the extremely localized effect of ALA. Consequently, through the layer-by-layer phase control of ALA, the dielectric constant of the upper-TiO2 was enhanced by 25% by applying ALA, leading to an increase in a capacitance density of 27% of the TZT capacitor, whereas a low leakage current density of ∼10-8 A/cm2 was maintained (at 1 V). In addition, the TZT capacitor on three-dimensional structures (aspect ratio of 5:1) shows a high capacitance density of up to 461 nF/mm2 owing to ALA.

Ultrathin Atomic Layer-Deposited CeO2 Overlayer for High-Performance Fuel Cell Electrodes.

Obtaining a catalyst with high activity and thermal stability is essential for high-performance energy conversion devices operating at an elevated temperature. Herein, the design and fabrication of a heterogeneous catalyst with an ultrathin CeO2 overlayer via atomic layer deposition (ALD) on Pt electrodes for low-temperature solid oxide fuel cells (LT-SOFCs) is reported. The cell with a CeO2-overcoated (five ALD cycles) Pt cathode shows lower activation resistance by 50% after a 10 h operation and higher thermal stability by a factor of 2 compared with the cell with a Pt-only cathode, which is known to be the best single catalyst at 450 °C. Eventually, a thin-film SOFC with a highly active and stable CeO2-overcoated cathode based on an anodized aluminum oxide (AAO) substrate demonstrates a high peak power density of 800 mW cm-2 at 500 °C, which is the highest performance ever reported for an AAO-based SOFC at this temperature.