Opportunity for band alignment manipulation of perovskite oxide stacks by interfacial dipole layer formation

Abstract

Dipole layers can be formed at epitaxial interfaces of perovskite oxides by intentionally inserting charged atomic layers. Perovskite oxides such as SrTiO3 (STO) can provide dielectrics with very high dielectric constants, but their bandgaps are so small that the suppression of leakage current is one of the critical issues when they are applied for DRAM capacitors. However, their conduction band offset will be manipulated if we can control the dipole layer formation. In this study, we investigated the opportunities of band alignment manipulation using the interface dipole effect especially focusing on the number of charge-introducing atomic layers. STO/LaAlO3 (LAO)/SrRuO3(SRO) stacks were fabricated by pulsed laser deposition method, to demonstrate the modulation of the band alignment at STO/SRO interface as large as ± 0.5 eV, when we change the number of inserted atomic layers of LAO.