  Through a combination of monitoring the Raman spectral characteristics of 2D
materials grown on copper catalyst layers, and wafer scale automated detection
of the fraction of transferred material, we reproducibly achieve transfers with
over 97.5% monolayer hexagonal boron nitride and 99.7% monolayer graphene
coverage, for up to 300 mm diameter wafers. We find a strong correlation
between the transfer coverage obtained for graphene and the emergence of a
lower wavenumber 2D- peak component, with the concurrent disappearance of the
higher wavenumber 2D+ peak component during oxidation of the catalyst surface.
The 2D peak characteristics can therefore act as an unambiguous predictor of
the success of the transfer. The combined monitoring and transfer process
presented here is highly scalable and amenable for roll-to-roll processing.
