Band structures and band offsets of high K dielectrics on Si

Various high dielectric constant oxides will be used as insulator in ferroelectric memories, dynamic random access memories, and as the gate dielectric material in future complementary metal oxide semiconductor (CMOS) technology. These oxides which have moderately wide bandgaps provide a good test of our understanding of Schottky barrier heights and band offsets at semiconductor interfaces. Metal induced gap states (MIGS) are found to give a good description of these interfaces. The electronic structure and band offsets of these oxides are calculated. It is found that Ta2O5 and SrTiO3 have small or vanishing conduction band offsets on Si. La2O3, Y2O3, ZrO2, HfO2, Al2O3 and silicates like ZrSiO4 have offsets over 1.4 eV for both electrons and holes, making them better gate dielectrics.