Abstract
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.
Highlights
Hexagonal boron nitride (h-BN) is a well-known member of the 2D family of materials, isostructural to graphene, but with distinct properties
Pre-growth conditioning of Fe foils towards large monolayer h-BN domains We focus on widely available, low-cost, standard purity (99.8%), polycrystalline Fe foils to demonstrate that our process is sufficiently contamination tolerant and does not require single crystal substrate preparation or excessive metallurgical processing
We find that the surface or near-surface contamination of Fe foils often comprises significant quantities of localised carbon (supplementary figures S1(a)–(d)), which we suggest leads to the observed preferential h-BN nucleation
Summary
Commons Attribution 4.0 Keywords: hexagonal boron nitride, large crystal, monolayer, chemical vapor deposition, 2D materials, transfer, encapsulation licence. Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, and 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 the balance between dissolved oxygen and carbon. A simple pre-growth conditioning step of the iron foils enables us to tailor an errortolerant scalable CVD process to give exceptionally large h-BN monolayer domains. We demonstrate wafer-scale (2′′) production and utilise this h-BN as a protective layer for graphene towards integrated (opto-)electronic device fabrication
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