Dielectric properties and electrical conduction of high-k LaGdO$_{3}$ ceramics*

The temperature and frequency dependent dielectric properties and leakage conduction mechanism in LaGdO$_{3}$ (LGO) ceramics have been studied and this material has been identified as a potential high-k candidate for the future complementary metal-oxide-semiconductor (CMOS) and dynamic random access memory (DRAM) technology nodes. The dielectric constant and the loss tangent at 100 kHz were $\sim $21.5 and $\sim $0.003 respectively at ambient conditions without any significant temperature and voltage dependence. The ac conductivity showed the typical features of universal dynamic response (UDR) and obey the double power law $\sigma _{ac} =\sigma _{dc} +A\omega ^{n_1 }+B\omega ^{n_2 }$ with three types of temperature dependent conduction processes involved; i) a dc plateau ($<$ 3 kHz) due to long range translational hopping, ii) a mid frequency region due to the short range hopping (3 -- 100 kHz), and iii) a high frequency region due to localized or reorientational hopping (100 -- 1000kHz). The temperature dependent dc conductivity followed the Arrhenius relation with activation energies of 0.05eV in the 200 -- 400 K range and 0.92 eV in the 400 -- 600 K range. The leakage current behavior revealed bulk limited Poole-Frenkel (PF) conduction mechanism with very low leakage current density (2 nA / cm$^{2}$ at 5.7 kV/cm).