Dominant role of oxygen vacancies in electrical properties of unannealed LaAlO3/SrTiO3 interfaces

摘要

We report that in unannealed LaAlO3/SrTiO3 (LAO/STO) heterostructures thecritical thickness for the appearance of the two-dimensional electron gas canbe less than 4 unit cell (uc), the interface is conducting even for STOsubstrates with mixed terminations and the low-temperature resistance upturn inLAO/STO heterostructures with thick LAO layers strongly depends on laserfluence. Our experimental results provide fundamental insights into thedifferent roles played by oxygen vacancies and polarization catastrophe in thetwo-dimensional electron gas in crystalline LAO/STO heterostructures.