Browsing by Author "Robertson, John"

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    From growth surface to device interface: preserving metallic Fe under monolayer hexagonal boron nitride
    (American Chemical Society, 2017-08-08) Caneva, Sabina; Martin, Marie-Blandine; D'Arsie, Lorenzo; Aria, Adrianus Indrat; Sezen, Hikmet; Amati, Matteo; Gregoratti, Luca; Sugime, Hisashi; Esconjauregui, Santiago; Robertson, John; Hofmann, Stephan; Weatherup, Robert S.
    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.