Extrinsic and Intrinsic Charge Transfer at Interfaces of Membrane‐Based Oxide Heterostructures

ABSTRACT Engineering complex oxide heterostructures and their interfaces has revealed a plethora of emergent electronic and magnetic properties. To achieve these functionalities beyond conventional epitaxy, building heterogeneous integrated electronic architectures have been possible from the advances in free‐standing oxides and their integration with semiconductors. However, to harness the physical phenomena of oxides in such co‐integrated environments, it is necessary to achieve atomically defined membrane‐based oxide heterostructures and subsequent control of charge‐transfer. Here, we report on the direct growth‐control of the surface termination of SrTiO 3 membranes, eliminating any B‐HF requirements, and subsequent transfer of TiO 2 ‐terminated SrTiO 3 membranes onto silicon (Si) via a sacrificial layer route. This approach yields atomically defined step‐terraced membrane‐based substrates on silicon support. By systematic growth control of LaAlO 3 on these templates, we demonstrate distinct signatures of oxygen‐vacancy‐induced (ionic) and intrinsic (electronic) charge transfer mechanisms. A systematic crossover between these processes is observed, based on near‐ambient pressure XPS, probing reversible and irreversible contributions of interfacial charge transfer during redox‐cycling. These results indicates that TiO 2 ‐termination in the oxide membrane may have been achieved, which is a prerequisite for tailoring and fine‐tuning membrane‐based oxide heterointerfaces for electronic and ionic phenomena in confined systems beyond conventional epitaxy.