  Hexagonal boron nitride (h-BN) is the only known material aside from graphite
with a structure composed of simple, stable, non-corrugated atomically thin
layers. While historically used as lubricant in powder form, h-BN layers have
become particularly attractive as an ultimately thin insulator. Practically all
emerging electronic and photonic device concepts rely on h-BN exfoliated from
small bulk crystallites, which limits device dimensions and process
scalability. Here, we address this integration challenge for mono-layer h-BN
via a chemical vapour deposition process that enables crystal sizes exceeding
0.5 mm starting from commercial, reusable platinum foils, and in unison allows
a delamination process for easy and clean layer transfer. We demonstrate
sequential pick-up for the assembly of graphene/h-BN heterostructures with
atomic layer precision, while minimizing interfacial contamination. Our process
development builds on a systematic understanding of the underlying mechanisms.
The approach can be readily combined with other layered materials and opens a
scalable route to h-BN layer integration and reliable 2D material device layer
stacks.
