Surface Amorphous Oxides Induced Electron Transfer into Complex Oxide Heterointerfaces

Abstract Complex oxide heterointerfaces are interesting because they host many exotic emergent phenomena and have potential for unconventional oxide electronics. Crucial to explore these phenomena and applications is controlling electron transfer. In the past, this has been difficult to achieve in many heterointerfaces such as LaAlO₃/SrTiO₃ fabricated on SrO‐terminated SrTiO₃, while a great success has been made in LaAlO₃/SrTiO₃ fabricated on TiO₂‐terminated SrTiO₃. Here, a variety of (both TiO₂‐ and SrO‐terminated) SrTiO₃‐based heterostructures (not limited to LaAlO₃/SrTiO₃) are capped with different kinds of amorphous oxides prepared at room temperature. It is found that more than 10¹⁴ cm⁻² electrons can be induced into heterointerfaces that are originally either conducting or insulating. By a thorough examination of various combinations between different heterostructues and different amorphous oxides, it is concluded that the observed effect is dominated by electron transfer from surface amorphous oxides into complex oxide heterointerfaces.