Publication Type:Journal Article
Source:Applied Physics Letters, American Institute of Physics Inc., Volume 104, Number 21 (2014)
Keywords:Atoms, Coincidence site lattices, Conduction-band minimum, Density function theory calculations, Electronic structure, Experimental methods, Heterojunction interfaces, Heterojunctions, Interfacial electronic structure, Lattice-mismatched, Probability density function, Valence-band maximums
Heterojunction interfaces between metal oxides are often highly lattice mismatched. The atomic and electronic structures of such interfaces, however, are not well understood. We have synthesized Cu2O/TiO2 heterojunction thin films with 13% lattice mismatch and studied the interface via experimental methods and large-scale density function theory calculations of supercells containing ∼1300 atoms. We find that an interface of epitaxial quality is formed via a coincidence site lattice of 8 Cu2O unit cells matching 9 TiO2 unit cells. Calculations reveal the existence of a dislocation core of the O sublattices at the interface and a random arrangement of one layer of interfacial Cu atoms. The interfacial electronic structure is found to be mostly determined by the interfacial Cu distribution, rather than by the O dislocation core. The conduction band minimum and valence band maximum states are spatially separated, and there is no strongly localized state near the core. © 2014 AIP Publishing LLC.
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