Reaction and Energy Levels at Oxide–Oxide Heterojunction Interfaces

Abstract Oxide–oxide heterojunction interfaces (OHIs) are foundations for many applications such as transistors, optoelectronic devices, and chemical catalysis. The formation of OHIs involves complex events such as charge transfer, interfacial diffusion, and chemical reactions. These events collectively contribute to an OHI's energy structure and to its ability to perform an intended application. Here, multiple MoO₃/oxide interfaces are studied at which changes in multiple oxidation states Mo^x+ can be easily tracked. For the formation of reactive interfaces, it is found that the primary driving force behind the reduction of MoO₃ is redox reactions at the interfaces. For the nonreactive interface, the reduction of MoO₃ occurs as a result of various factors such as oxygen deficiency. At these OHIs, band bending and formation of interface dipole are observed. It is discovered that the degrees of interface dipole and work function at the OHIs scale linearly as a function of the contacting oxide's work function. These findings provide the guide in designing OHIs for a specific application.