High-permittivity HfO2 and ZrO2 based oxides grown by atomic layer deposition are investigated. Both ZrO2 and HfO2 are materials of high chemical stability and may form relatively stable interface with silicon substrate. To amorphize the structure and increase the resistivity of the dielectric layer, the high-permittivity material was mixed with another high band-gap material such as Al2O3. This work presents experimental results obtained from electrical characterization of metal-insulator-semiconductor structures based on these dielectrics. Capacitance-voltage, deep-level transient spectroscopy and conductance transient analysis have been used to prove the promising performances of these advanced materials to obtain good interface quality in the incoming CMOS technology. Mixtures of nanolayers of zirconium or hafnium oxide and aluminium oxide yield the best behaviour. They show acceptable density levels of disordered-induced gap states in the insulator level and interface state densities similar to those of stoichiometric oxides. (C) 2003 Elsevier Ltd. All rights reserved.