From Growth Surface to Device Interface: Preserving Metallic Fe under Monolayer Hexagonal Boron Nitride

Sabina Caneva, Marie-Blandine Martin, Lorenzo D'Arsie, Adrianus I. Aria, Hikmet Sezen, Matteo Amati, Luca Gregoratti, Hisashi Sugime, Santiago Esconjauregui, John Robertson, Stephan Hofmann, Robert S. Weatherup

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We investigate the interfacial chemistry between Fe catalyst foils and monolayer hexagonal boron nitride (h-BN) following chemical vapor deposition and during subsequent atmospheric exposure, using scanning electron microscopy, X-ray photoemission spectroscopy, and scanning photoelectron microscopy. We show that regions of the Fe surface covered by h-BN remain in a metallic state during exposure to moist air for ∼40 h at room temperature. This protection is attributed to the strong interfacial interaction between h-BN and Fe, which prevents the rapid intercalation of oxidizing species. Local Fe oxidation is observed on bare Fe regions and close to defects in the h-BN film (e.g., domain boundaries, wrinkles, and edges), which over the longer-term provide pathways for slow bulk oxidation of Fe. We further confirm that the interface between h-BN and metallic Fe can be recovered by vacuum annealing at ∼600 °C, although this is accompanied by the creation of defects within the h-BN film. We discuss the importance of these findings in the context of integrated manufacturing and transfer-free device integration of h-BN, particularly for technologically important applications where h-BN has potential as a tunnel barrier such as magnetic tunnel junctions.
    Original languageEnglish
    Pages (from-to)29973-29981
    JournalACS Applied Materials and Interfaces
    Volume9
    Issue number35
    DOIs
    Publication statusPublished - 7 Aug 2017

    Keywords

    • hexagonal boron nitride (h-BN)
    • iron (Fe)
    • interfacial chemistry
    • X-ray photoelectron spectroscopy (XPS)
    • chemical vapor deposition (CVD)

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