Dielectric Characterization of Rare-Earth Based Ceramics, High-k Materials: Future of Microelectronics

Abstract

In this study, the nano-crystalline rare earth oxides RE2O3 (RE= Er, Ho,Dy) was synthesized through the sol-gel technique. The effect of sintering temperature from 2500C to 14000C on structure, morphology, and electrical properties of the sol-gel synthesized RE2O3 was studied. The results were compared with the microcrystalline rare earth oxides RE2O3 purchased from the market. The synthesized rare earth oxides RE2O3 showed fiber like nanostructures with thickness varying for different materials. Dielectric properties at different sintering temperatures were measured in the frequency range 100Hz to 5MHz. The synthesized rare earth oxides RE2O3 had the highest dielectric constant at 6500C for erbium oxide and dysprosium oxide while highest dielectric constant for holmium oxide was observed at 850 0C. The behavior of the dissipation factor tan (δ) and ac conductivity (σac) for sol-gel synthesized erbium oxide was distinct from that of the purchased material. The dissipation factor tan (δ) was higher at low frequencies and then decreased with the increase in frequency. For the synthesized erbium and holmium oxide dissipation factors were smaller than purchased materials while for dysprosium oxide it was higher than purchased material. The synthesized materials sintered at different temperatures exhibited a similar sort of frequency-dependent response for permittivity (є) and resistivity (ρ). This was in accordance with Koop’s theory of dielectrics. For the microcrystalline rare earth oxides RE2O3 materials, frequency dependence of permittivity and resistivity was not uniform. The results showed that sol-gel synthesized rare earth oxides RE2O3 (RE= Er, Ho, Dy) could be good candidates for different high-k applications