Electronic Structure and Band Alignment at the NiO and SrTiO3 p-n Heterojunctions

Kelvin H.L. Zhang, Rui Wu, Fengzai Tang, Weiwei Li, Freddy E. Oropeza, Liang Qiao, Vlado K. Lazarov, Yingge Du, David J. Payne, Judith L. Macmanus-Driscoll, Mark G. Blamire

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Understanding the energetics at the interface, including the alignment of valence and conduction bands, built-in potentials, and ionic and electronic reconstructions, is an important challenge in designing oxide interfaces that have controllable multifunctionalities for novel (opto-)electronic devices. In this work, we report detailed investigations on the heterointerface of wide-band-gap p-type NiO and n-type SrTiO3 (STO). We show that despite a large lattice mismatch (∼7%) and dissimilar crystal structure, high-quality NiO and Li-doped NiO (LNO) thin films can be epitaxially grown on STO(001) substrates through a domain-matching epitaxy mechanism. X-ray photoelectron spectroscopy studies indicate that NiO/STO heterojunctions form a type II "staggered" band alignment. In addition, a large built-in potential of up to 0.97 eV was observed at the interface of LNO and Nb-doped STO (NbSTO). The LNO/NbSTO p-n heterojunctions exhibit not only a large rectification ratio of 2 × 103 but also a large ideality factor of 4.3. The NiO/STO p-n heterojunctions have important implications for applications in photocatalysis and photodetectors as the interface provides favorable energetics for facile separation and transport of photogenerated electrons and holes.

    Original languageEnglish
    Pages (from-to)26549-26555
    Number of pages7
    JournalACS Applied Materials and Interfaces
    Volume9
    Issue number31
    DOIs
    Publication statusPublished - 11 Aug 2017

    Keywords

    • band offset
    • electronic structure
    • NiO
    • oxide heterojunctions
    • perovskite oxide
    • photocatalysis
    • transparent conducting oxides

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