Anomalous dielectric dispersion in tantalum oxide films prepared by RF sputtering

Tantalum oxide thin films prepared by rf sputtering show anomalous dielectric dispersion in the low frequency range. Very high dielectric constant and dielectric loss (tan delta) are observed in the frequency range below 10 kHz. The dielectric loss (tan delta) peak shifts toward higher frequencies with temperature. In addition, this peak shows strong thickness dependence which excludes the possibility of ordinal dipolar polarization. These characteristics are explained in terms of interfacial polarization based on the Maxwell-Wagner mechanism. The thickness of the aluminum oxide blocking layer on the electrode surface has been evaluated to be approximately 38 nm from experimental results.