Effects of the Ti buffer layer on crystallization processes of lead-zirconate-titanate (PZT) films by the sol-gel deposition technique were investigated. The Ti buffer layer was deposited on a Pt/TiN/SiO2/Si substrate by electron beam evaporation at the back-pressure of 1×10-11 Torr. Homogeneous crystalline PZT film of perovskite structure with fine grains were successfully obtained on the substrate with a Ti buffer layer. In contrast, a rosette-structure film which consists of large grains surrounded by a second phase was formed on a pure Pt surface. Ti existing at the interface between Pt and PZT acts as nuclei, and affects the growth of fine grains. Furthermore, leakage current density was drastically reduced from 5×10-5 A/cm2 to 6×10-9 A/cm2 at 4 V for 200-nm-thick film formed on a substrate with a buffer layer. Crystalline orientations and microstructures of PZT films were strongly dependent on the equivalent thickness of the buffer layer and there was an optimum thickness. When the equivalent thickness of the buffer layer was 2 nm, PZT showed <111>-preferred orientation and a homogeneous film structure with fine grains on the <111>-oriented Pt/SiO2/Si substrate.

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The response to an AC magnetic field of a type I1 superconducting single-crystal Pb-Na cylindrical rod has been observed as a function of longitudinal DC fields. The results show two different regimes of flux pinning within the specimen. At low fields in the mixed state the specimen is largely reversible in the bulk and all pinning appears to be at the surface. In a field close to H,,, there is a peak region where bulk pinning rapidly dominates. Evidence for these regimes is discussed.

This paper describes the dielectric properties of (Ba, Sr)TiO3 (BST) thin films deposited by rf magnetron sputtering, focusing on their correlation with the oxygen vacancy density in the films. The dielectric properties specific to the BST films can be explained by considering the influence of the dielectric relaxation phenomenon following a power law dependence on time in the time-domain measurement and on frequency in the frequency-domain measurement. From an electrical comparison of the films with and without post-annealing in oxygen ambient, it is derived that charging/discharging electrons at oxygen vacancies in the interfacial Schottky depletion layer, whose width is modulated by the applied voltage, are responsible for the observed dielectric properties. Preliminary results of the oxygen vacancy density measurement using a gas-solid oxygen isotopic exchange reaction showed that the higher the post-annealing temperature, the lower the oxygen vacancy density.

Current-voltage characteristics of SrTiO3 thin films prepared on Pt electrodes by electron-cyclotron-resonance sputtering have been studied. The leakage current characteristics of the films show an ohmiclike conduction for electric field strengths lower than about 1 MV/cm, while the leakage current for higher electric field strengths is limited by Schottky emission. These ohmiclike leakage characteristics in the low-electric-field region show strong dependences on the measurement conditions, namely, the values of voltagestep and measurement delaytime in the conventional stepwise current-voltage ramps. This result is attributed to the absorption current due to the dielectric relaxation phenomena of the SrTiO3 capacitor. The overall current-voltage characteristics can be explained by Schottky emission from the Pt electrode.