In this work, we report on two properties of the oxidation of tantalum silicide (Ta2Si) on SiC substrates making this material of interest as insulator for many wide bandgap or compound semiconductors. The relatively high oxidation rate of tantalum silicide to form high-k insulator layers and its ability for being oxidized in diluted N2O ambient in a manner similar to the oxidation in O-2 are investigated. Metal-insulator-semiconductor capacitors have been used to establish the actual applicability and constrain of the high-k insulator depending on the oxidation conditions. At 1050 degrees C, the reduction of the oxidation time from 1 h to 5 min affects primordially the SiOx interfacial layer formed between the bulk insulator and the substrate. This interfacial layer strongly influences the metal-insulator-semiconductor performances of the oxidized Ta2Si layer. The bulk insulator basically remains unaffected although some structural differences arise when the oxidation is performed in N2O. (c) 2006 Elsevier B.V. All rights reserved.