Space-charge polarisation dielectric behaviour of precursor derived monoclinic HfO2

Hafnium dioxide (HfO2) attracts attention because of its high dielectric constant, wide band gap, and also since it can be quite effortlessly grown on the surface of a silicon substrate. In this work, dense ceramics of hafnium oxide in the monoclinic phase was synthesised from a liquid precursor of hafnium tri-methyl-tetra-oxide (Hf [O(CH3)(3)](4)) and sintered by conventional techniques. The electrical properties of the sample were studied by broadband dielectric spectroscopy over a wide range of frequencies (10(-1 )10(6) Hz) and temperature range (300-670 K). The temperature and frequency dependencies of the dielectric response exemplify high stability of the material in the investigated temperature range. The dielectric constant of conventionally sintered ceramics at room temperature is ~13. The frequency dispersion of ceramics was revealed and analysed over the entire investigated temperature range. It is shown that the main contribution to the response is made by low frequency charge polarisation. DC conductivity of HfO2 has a thermally activated character with an activation energy of 1.2 eV in the temperature range below 600 K and 0.9 eV above 600 K. The conductivity is determined by oxygen vacancies.