Engineering the work function of armchair graphene nanoribbons using strain and functional species: A first principles study

Xihong Peng, Fu Tang, Andrew Copple

    Research output: Contribution to journalArticlepeer-review

    78 Scopus citations

    Abstract

    First principles density functional theory calculations were performed to study the effects of strain, edge passivation, and surface functional species on the structural and electronic properties of armchair graphene nanoribbons (AGNRs), with a particular focus on the work function. The work function was found to increase with uniaxial tensile strain and decrease with compression. The variation of the work function under strain is primarily due to the shift of the Fermi energy with strain. In addition, the relationship between the work function variation and the core level shift with strain is discussed. Distinct trends of the core level shift under tensile and compressive strain were discovered. For AGNRs with the edge carbon atoms passivated by oxygen, the work function is higher than for nanoribbons with the edge passivated by hydrogen under a moderate strain. The difference between the work functions in these two edge passivations is enlarged (reduced) under a sufficient tensile (compressive) strain. This has been correlated to a directindirect bandgap transition for tensile strains of about 4% and to a structural transformation for large compressive strains at about 12%. Furthermore, the effect of the surface species decoration, such as H, F, or OH with different covering density, was investigated. It was found that the work function varies with the type and coverage of surface functional species. Decoration with F and OH increases the work function while H decreases it. The surface functional species were decorated on either one side or both sides of AGNRs. The difference in the work functions between one-sided and two-sided decorations was found to be relatively small, which may suggest an introduced surface dipole plays a minor role.

    Original languageEnglish (US)
    Article number075501
    JournalJournal of Physics Condensed Matter
    Volume24
    Issue number7
    DOIs
    StatePublished - Feb 22 2012

    ASJC Scopus subject areas

    • General Materials Science
    • Condensed Matter Physics

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