Hafnium oxide (HfO2) films were grown on SiO2/Si and Pt/Ti/SiO2/Si substrates by a sol-gel method, and their crystalline structure, microstructure and electrical properties were investigated. XRD analysis indicated that the monoclinic HfO2 films can be obtained by annealing at 500 degrees C. A transmission electron microscopy (TEM) image showed that the films were grown as a spherulite grain structure with a mean grain size of approximately 15 nm. The dielectric constant of the HfO2 films of 300 nm was approximately 21.6, and the current-voltage measurements showed that the leakage current density of the HfO2 films was approximately 1.14 x 10(-5)A/cm(2) at an applied electric field of 100 kV/cm. (c) 2005 Elsevier B.V. All rights reserved.