Intrinsic electrical properties of Au/Nb-doped SrTiO 3 ͑001͒ ͑STO:Nb͒ Schottky junctions, fabricated using a proper surface treatment of the STO:Nb and in situ deposition of Au, were investigated in detail. Current-voltage characteristics and photocurrent-wavelength characteristics have shown a temperature-dependent and voltage-dependent Schottky barrier height, while capacitance-voltage characteristics have shown a temperature-independent flat band voltage. Using a temperature-dependent and field-dependent permittivity of the STO in the framework of Devonshire theory, we have performed computer simulation of the Schottky barrier potential to analyze the electrical properties of the junction. It is found that an intrinsic low permittivity layer at the Au/STO:Nb interface explains all the temperature dependence of the electrical properties.

Lanthanum oxide thin films were fabricated on Si substrates by the metallorganic chemical vapor deposition ͑MOCVD͒ method at substrate temperatures ranging from 400 to 650°C. From the results of X-ray photoelectron spectroscopy ͑XPS͒, X-ray diffraction ͑XRD͒, cross-sectional scanning transmission electron microscopy ͑STEM͒, and energy-dispersive X-ray ͑EDX͒ analyses, the enhanced chemical reaction at the interface between the Si substrate and the films was revealed, which results in the generation of an interfacial layer of SiO 2 ͑1-2 nm thick͒ and lanthanum silicate at all the experimental substrate temperatures. We found that a thin silicon oxynitride layer on the Si substrate is effective in suppressing the interfacial reaction and in increasing the dielectric constant of the lanthanum oxide deposited on it. The thin silicon oxynitride layer is also effective in reducing the leakage current through the film. For the stacked La-oxide/SiON film, the dielectric constant of the lanthanum oxide film was 19 and the leakage current density was 3 ϫ 10 Ϫ6 A/cm 2 at the oxide voltage of 1 V for a film with an equivalent oxide thickness of 2.4 nm.

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