TEM characterization of BN films grown on metallic substrates by CVD

International audienceBoron nitride (BN) is identified as a strategic material for many purposes related to the integration of graphene and 2D materials in devices and the fabrication of van der Waals heterostructures. Thus, it becomes mandatory to have scalable synthesis and characterization procedures for providing suitable and reliable boron nitride material according to these three identified needs. In this work, we are interested in the TEM characterization of boron nitride films grown on copper or nickel foil by CVD, using H2 as a carrier gas and borazine as BN source. The growth on polycrystalline copper foil leads to few nanometer thick films, with a not highly crystallized turbostratic structure. These films exhibit a rough surface at the atomic scale, which is not suitable as a graphene substrate but can be used as capping material of a 2D crystal in a device. Conversely, highly crystalline boron nitride is synthesized on polycrystalline nickel foil. We performed a detailed analysis of the influence of nickel grain orientation on the structure of the BN layers in terms of morphology, thickness, orientation, domain size etc

Thermal Stability of Thin hexagonal Boron Nitride grown by MOVPE on Epigraphene

International audiencePassivating graphene with a layer of hexagonal boron nitride (hBN) is known to protect it from environment effects that degrade its mobility. However, BN is hard to grow on graphene because of the lack of surface dangling bonds. Here, we report the growth of thin BN films (down to 10 nm) on monolayer epigraphene grown on silicon carbide single-crystal substrates using metal-organic vapor phase epitaxy (MOVPE). The BN film has continuous coverage on the epigraphene surface, with smooth morphology. Particles consisting of layered BN are also observed on the surface with a higher density at the step edges. High-Resolution Scanning Transmission Electron Microscopy reveals high structural quality BN layers, with a clean and abrupt interface with graphene. The BN/epigraphene/SiC heterostructure is stable up to high temperature (1550 oC), and annealing improves its crystallinity. These results show that MOVPE growth technique has a potential for large-scale production of BN fully coated graphene and high-temperature applications

Thermal Stability of Thin hexagonal Boron Nitride grown by MOVPE on Epigraphene

International audiencePassivating graphene with a layer of hexagonal boron nitride (hBN) is known to protect it from environment effects that degrade its mobility. However, BN is hard to grow on graphene because of the lack of surface dangling bonds. Here, we report the growth of thin BN films (down to 10 nm) on monolayer epigraphene grown on silicon carbide single-crystal substrates using metal-organic vapor phase epitaxy (MOVPE). The BN film has continuous coverage on the epigraphene surface, with smooth morphology. Particles consisting of layered BN are also observed on the surface with a higher density at the step edges. High-Resolution Scanning Transmission Electron Microscopy reveals high structural quality BN layers, with a clean and abrupt interface with graphene. The BN/epigraphene/SiC heterostructure is stable up to high temperature (1550 oC), and annealing improves its crystallinity. These results show that MOVPE growth technique has a potential for large-scale production of BN fully coated graphene and high-temperature applications