Electronic Structure and Band Alignment at an Epitaxial Spinel/Perovskite Heterojunction

L Qiao, W Li, H Y Xiao, H M Meyer, X L Liang, N V Nguyen, W J Weber, M D Biegalski

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The electronic properties of solid solid interfaces play critical roles in a variety of technological applications. Recent advances of film epitaxy and characterization techniques have demonstrated a wealth of exotic phenomena at interfaces of oxide materials, which are critically dependent on the alignment of their energy bands across the interface. Here we report a combined photoemission and electrical investigation of the electronic structures across a prototypical spinel/perovskite heterojunction. Energy-level band alignment at an epitaxial Co3O4/SrTiO3(001) heterointerface indicates a chemically abrupt, type I heterojunction without detectable band bending at both the film and substrate. The unexpected band alignment for this typical p-type semiconductor on SrTiO3 is attributed to its intrinsic d-d interband excitation, which significantly narrows the fundamental band gap between the top of the valence band and the bottom of the conduction band. The formation of the type I heterojunction with a flat-band state results in a simultaneous confinement of both electrons and holes inside the Co3O4 layer, thus rendering the epitaxial Co3O4/SrTiO3(001) heterostructure to be a very promising material for high-efficiency luminescence and optoelectronic device applications.
    Original languageEnglish
    Pages (from-to)14338-14344
    Number of pages7
    JournalACS applied materials & interfaces
    Volume6
    Issue number16
    DOIs
    Publication statusPublished - 2014

    Keywords

    • spinel/perovskite heterojunction
    • electronic structure
    • band alignment
    • photoemission
    • ray photoemission spectra
    • thin-films
    • precise determination
    • cobalt
    • oxides
    • core-level
    • srtio3
    • co3o4
    • interface
    • surfaces
    • offsets

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