Oxidising and carburising catalyst conditioning for the controlled growth and transfer of large crystal monolayer hexagonal boron nitride

Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, but also recently as an active material for applications ranging from hyperbolic metasurfaces to room temperature single-photon sources. Cost-effective, scalable and high quality growth techniques for h-BN layers are critically required. We utilise widely-available iron foils for the catalytic chemical vapour deposition (CVD) of h-BN and report on the significant role of bulk dissolved species in h-BN CVD, and specifically, the balance between dissolved oxygen and carbon. A simple pre-growth conditioning step of the iron foils enables us to tailor an error-tolerant scalable CVD process to give exceptionally large h-BN monolayer domains. We also develop a facile method for the improved transfer of as-grown h-BN away from the iron surface by means of the controlled humidity oxidation and subsequent rapid etching of a thin interfacial iron oxide; thus, avoiding the impurities from the bulk of the foil. We demonstrate wafer-scale (2'') production and utilise this h-BN as a protective layer for graphene towards integrated (opto-)electronic device fabrication

The Role and Control of Residual Bulk Oxygen in the Catalytic Growth of 2D Materials

We systematically study the effects of residual oxygen in the bulk of Cu foil catalysts on the chemical vapor deposition (CVD) of graphene. While oxidation is widely used to remove impurities in metal catalysts and to control the nucleation density of graphene, we show that minute concentrations of residual bulk oxygen can significantly deteriorate the quality of as-grown graphene highlighted by an increased Raman D/G ratio, increased propensity to postgrowth etching, and increased fraction of multilayer graphene nucleation. Starting from commercial Cu foils, we show that a simple hydrogen annealing step after the initial oxidation allows us to lower the residual oxygen level as measured by time-of-flight secondary ion mass spectrometry to produce graphene of significantly higher quality. This can be effectively combined with a short hydrocarbon exposure time of 10 min to achieve near full monolayer graphene coverage, suitable for emerging industrial applications. We show that residual oxygen can have an equally significant impact on Fe-catalyzed h-BN CVD and discuss the underlying mechanisms with parallels to well-known processes in metallurgy, catalysis, and vacuum science

The Role and Control of Residual Bulk Oxygen in the Catalytic Growth of 2D Materials

We systematically study the effects of residual oxygen in the bulk of Cu foil catalysts on the chemical vapor deposition (CVD) of graphene. While oxidation is widely used to remove impurities in metal catalysts and to control the nucleation density of graphene, we show that minute concentrations of residual bulk oxygen can significantly deteriorate the quality of as-grown graphene highlighted by an increased Raman D/G ratio, increased propensity to postgrowth etching, and increased fraction of multilayer graphene nucleation. Starting from commercial Cu foils, we show that a simple hydrogen annealing step after the initial oxidation allows us to lower the residual oxygen level as measured by time-of-flight secondary ion mass spectrometry to produce graphene of significantly higher quality. This can be effectively combined with a short hydrocarbon exposure time of 10 min to achieve near full monolayer graphene coverage, suitable for emerging industrial applications. We show that residual oxygen can have an equally significant impact on Fe-catalyzed h-BN CVD and discuss the underlying mechanisms with parallels to well-known processes in metallurgy, catalysis, and vacuum science

Oxidising and carburising catalyst conditioning for the controlled growth and transfer of large crystal monolayer hexagonal boron nitride

© 2020 IOP Publishing Ltd. Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, but also recently as an active material for applications ranging from hyperbolic metasurfaces to room temperature single-photon sources. Cost-effective, scalable and high quality growth techniques for h-BN layers are critically required. We utilise widely-available iron foils for the catalytic chemical vapour deposition (CVD) of h-BN and report on the significant role of bulk dissolved species in h-BN CVD, and specifically, the balance between dissolved oxygen and carbon. A simple pre-growth conditioning step of the iron foils enables us to tailor an error-tolerant scalable CVD process to give exceptionally large h-BN monolayer domains. We also develop a facile method for the improved transfer of as-grown h-BN away from the iron surface by means of the controlled humidity oxidation and subsequent rapid etching of a thin interfacial iron oxide; thus, avoiding the impurities from the bulk of the foil. We demonstrate wafer-scale (2″) production and utilise this h-BN as a protective layer for graphene towards integrated (opto-)electronic device fabrication

Oxidising and carburising catalyst conditioning for the controlled growth and transfer of large crystal monolayer hexagonal boron nitride

Funder: H2020 Marie Skłodowska-Curie Actions; doi: https://doi.org/10.13039/100010665Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, but also recently as an active material for applications ranging from hyperbolic metasurfaces to room temperature single-photon sources. Cost-effective, scalable and high quality growth techniques for h-BN layers are critically required. We utilise widely-available iron foils for the catalytic chemical vapour deposition (CVD) of h BN and report on the significant role of bulk dissolved species in h-BN CVD, and specifically, the balance between dissolved oxygen and carbon. A simple pre-growth conditioning step of the iron foils enables us to tailor an error-tolerant scalable CVD process to give exceptionally large h-BN monolayer domains. We also develop a facile method for the improved transfer of as-grown h-BN away from the iron surface by means of the controlled humidity oxidation and subsequent rapid etching of a thin interfacial iron oxide; thus, avoiding the impurities from the bulk of the foil. We demonstrate wafer-scale (2 inch) production and utilise this h-BN as a protective layer for graphene towards integrated (opto) electronic device fabrication.European Union's Horizon 2020 research and innovation program under Grant Agreement No number 785219. European Union's Horizon 2020 research and innovation program under Grant Agreement No number 796388. the Royal Commission for the Exhibition of 1851. EU Marie Skłodowska-Curie Individual Fellowship (Global) under grant ARTIST (No. 656870). EPSRC (EP/P005152/1, and Doctoral Training Award EP/M508007/1). U.K. Department of Business, Energy and Industrial Strategy (NPL Project Number 121452)