(Invited) Theoretical Perspectives in Defect and Impurity Physics toward Materials Design for Oxides

Abstract

Doping oxides with foreign elements significantly varies their electronic and structural properties. Here we demonstrate that doping is actually useful for controlling interfacial structures and photoresponse properties of several oxide materials. Based on our theory, the difference in the interfacial structures of HfO2/Si and La2O3/Si is understood by migration of Si atoms into La2O3, turning the oxide into an oxygen absorber. Analogs to the mechanism of the formation of a silicate layer at La2O3/Si, we have suggested a practical solution for the removal of a redundant SiOx layer unintentionally formed at HfO2/Si by doping with a donor, Ta, into HfO2. The theory of doped oxides has been also exported to investigate several phenomena in photocatalysis reactions such as N-doped TiO2 and Cr-doped SrTiO3. Our results clearly show that the computational materials design is feasible for doped oxides.