The electronic and chemical properties of the interface region in the structures obtained by the passivation of epitaxial n-type 4H-SiC layers with bilayers consisting of a 5 nm-thick SiO2 or Al2O3 buffer film and high-kappa HfO2 layer were investigated. The main aim was to estimate the influence of the passivation approach on the interface effective charge density (Q(eff)) from the surface photovoltage (SPV) method and, in addition to determine the in-depth element distribution in the interface region from the Auger electron spectroscopy (AES) combined with Ar+ ion profiling. The structure HfO2/SiO2/4H-SiC exhibited slightly superior electronic properties in terms of Q(eff) (in the range of -10(11) q cm(-2)). (c) 2012 Elsevier B.V. All rights reserved.