The composition of Van-der-Waals heterostructures is conclusively determined
using a hybrid evaluation scheme of data acquired by optical microspectroscopy.
This scheme deploys a parameter set comprising both change in reflectance and
wavelength shift of distinct extreme values in reflectance spectra.
Furthermore, the method is supported by an accurate analytical model describing
reflectance of multilayer systems acquired by optical microspectroscopy. This
approach allows uniquely for discrimination of 2D materials like graphene and
hBN and, thus, quantitative analysis of Van-der-Waals heterostructures
containing structurally very similar materials. The physical model features a
transfer matrix method which allows for flexible, modular description of
complex optical systems and may easily be extended to individual setups. It
accounts for numerical apertures of applied objective lenses and a glass fiber
which guides the light into the spectrometer by two individual weighting
functions. The scheme is proven by highly accurate quantification of the number
of layers of graphene and hBN in Van-der-Waals heterostructures. In this
exemplary case, the fingerprint of graphene involves distinct deviations of
reflectance accompanied by additional wavelength shifts of extreme values. In
contrast to graphene the fingerprint of hBN reveals a negligible deviation in
absolute reflectance causing this material being only detectable by spectral
shifts of extreme values.Comment: 12 pages, 4 figure
