Band offsets of wide-band-gap oxides and implications for future electronic devices

TLDR

Wide‑band‑gap oxides such as SrTiO3 serve as critical tests for theories of Schottky barrier heights based on metal‑induced gap states and charge neutrality levels. The study reviews the theory and applies it to calculate Schottky barrier heights and band offsets for many high‑dielectric‑constant oxides on Pt and Si. First‑principles calculations were performed to screen oxides—including BaZrO3, ZrO2, HfO2, La2O3, Y2O3, HfSiO4, and Zr.

Abstract

Wide-band-gap oxides such as SrTiO3 are shown to be critical tests of theories of Schottky barrier heights based on metal-induced gap states and charge neutrality levels. This theory is reviewed and used to calculate the Schottky barrier heights and band offsets for many important high dielectric constant oxides on Pt and Si. Good agreement with experiment is found for barrier heights. The band offsets for electrons on Si are found to be small for many key oxides such as SrTiO3 and Ta2O5 which limit their utility as gate oxides in future silicon field effect transistors. The calculations are extended to screen other proposed oxides such as BaZrO3. ZrO2, HfO2, La2O3, Y2O3, HfSiO4, and ZrSiO4. Predictions are also given for barrier heights of the ferroelectric oxides Pb1−xZrxTiO3 and SrBi2Ta2O9 which are used in nonvolatile memories.