The properties of oxides with high-dielectric constant are being extensively studied for use as gate oxides. The criteria for choosing such oxides is discussed. The bonding at Si-oxide interfaces is considered in order to obtain an insulating interface. The stabilities of various atomic configurations of interface are compared, and their band offsets are calculated. The energy levels of point defects are calculated and the origin of fixed charge present is discussed. (C) 2004 Elsevier Ltd. All rights reserved.