Dy 2 O 3 is a promising candidate for future metal-oxide-semiconductor ͑MOS͒ gate dielectric applications. In this work, MOS capacitors and field-effect transistors with Dy 2 O 3 gate dielectric were fabricated. The maximum electron mobility was 339 cm 2 / V s. The time dependent dielectric breakdown ͑TDDB͒ of Dy 2 O 3 as a function of electric field and temperature was studied. It was observed that the Weibull slopes were independent of capacitor area and the Weibull slope increased with increasing Dy 2 O 3 thickness. The TDDB of Dy 2 O 3 followed the E model. The activation energy E a was linearly dependent on the electric field and the field acceleration parameter ␥ is independent of temperature.

Al/ZrO 2 /p-Si metal-insulator-semiconductor capacitors were fabricated. The ZrO 2 films were deposited by radio frequency magnetron sputtering. The X-ray photoelectron spectroscopy analysis shows the silicate interfacial layer formed between ZrO 2 and Si. The hysteresis and the density of positive oxide trapped charges of the capacitors from capacitance-voltage measurement were 230 mV and 8.8 ϫ 10 11 cm −2 , respectively. The equivalent oxide thickness of ZrO 2 was estimated to be 5.6 nm. The typical dielectric constant of 11.1 was calculated. With the A1 electrode biased negative, the conduction mechanism in the electrical field below 0.25 MV/cm and in the temperature range 375 K Ͻ T Ͻ 450 K was found to be ohmic emission. A model of thermally excited and hopping electrons was proposed to explain the mechanism of ohmic conduction current.In recent years, high-k dielectrics have attracted great attention for the advantaged property of high dielectric constant. Zirconium oxide ͑ZrO 2 ͒ is considered as a potential replacement of SiO 2 due to its high dielectric constant ͑20-25͒, 1-4 large energy bandgap ͑5.4 eV͒, high breakdown electric field ͑7-15 MV/cm͒, and low leakage current level. 2-4 The conduction mechanism in ZrO 2 thin films is an important subject for these applications. Chim et al. 5 found that the conduction mechanism for an Al/ZrO 2 /n-Si capacitor was PooleFrenkel emission in the electrical field between 2.0 and 3.2 MV/cm under positive gate bias. A barrier height of the interface of ZrO 2 and Si was 1.4 eV, calculated from a curve fitting of current density vs. electric field. Yamaguchi et al. 6 reported the conduction mechanism of Poole-Frenkel emission and measured the trap barrier height. The trap barrier height on the interface of ZrO 2 and Si was 1.0 and 1.5 eV, obtained by applying a positive gate voltage and X-ray photoelectron spectroscopy ͑XPS͒, respectively. Chang and Lin 7 showed that the conduction mechanism was dominated by Schottky emission at low electric field and by Poole-Frenkel emission at high electric field.In our previous work, 8 with the Al electrode biased negative, the conduction mechanism in the electrical field of 0.81 MV/ cm Ͻ E Ͻ 1.40 MV/cm and in the temperature range of 375 K Ͻ T Ͻ 450 K is found to be modified Schottky emission. The intrinsic barrier height between Al and ZrO 2 is 1.06 eV. At higher electrical fields of 1.50 MV/cm Ͻ E Ͻ 2.25 MV/cm and higher temperatures of 375 K Ͻ T Ͻ 450 K, the electrical conduction is dominated by modified Poole-Frenkel emission. The extracted trap level is 0.83 eV.In this present work, with the Al electrode biased negative, the conduction mechanism at lower electric field ͑Ͻ0.8 MV/cm͒ is further studied. The ohmic emission is considered due to a strong dependence on applied electric field and temperature. Furthermore, material properties are investigated by X-ray photoelectron spectroscopy ͑XPS͒ analysis. The electrical measurements, including current-voltage ͑I-V͒ and capacitance-voltage ͑C-V͒ characteristics, are performed on ...

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