High temperature conductance characteristics of LaAlO₃/ SrTiO₃-heterostructures under equilibrium oxygen atmospheres

The interface conductance of LaAlO₃/SrTiO₃ heterostructures was investigated under high temperature oxygen equilibrium. The dependence of the heterostructure's conductance on oxygen partial pressure (from 10-22 to 1 bar) and temperature (800 to 1100 K) was compared to the characteristic of SrTiO₃ single crystals, which is described in terms of a defect chemistry model. Up to 950 K the equilibrated heterostructures reveal an additional influence of a metallic-like conduction path with a very slight dependence on the oxygen partial pressure. Donor-type interface states which may result from either lattice distortions or A-site cation intermixing during processing are discussed as a possible origin for the exceptional interface conduction of LaAlO₃/SrTiO₃ heterostructures.