In this work we show a plasma-assisted process for the deposition of good quality a-SiO2 layers on 4H-SiC as a possible alternative to thermal oxidation. We used the plasma enhanced chemical vapor deposition (PECVD) technique for the growth of a-SiO2 layers on 4H-SiC using SiH4 and CO2 as precursor gases in H-2 dilution. We showed that good quality oxide layers could be obtained by this method, with a growth rate varying from 1.3 to 2.1 Angstrom/s, depending on the RF power. An estimation of the interface charge was obtained by high frequency capacitance voltage (HFCV) characteristic, obtaining values comparable to the ones typical of thermally grown oxides. This process was used for the growth of a-SiO2 insulating and protecting layers in the fabrication of Schottky diodes based on 4H-SiC, obtaining a breakdown voltage higher than 600 V. (C) 2004 Elsevier B.V. All rights reserved.