An efficient route to synthesize macroscopic amounts of graphene is highly desired and a bulk characterization of such samples, in terms of the number of layers, is equally important. We present a Raman spectroscopy-based method to determine the distribution of the number of graphene layers in chemically exfoliated graphene. We utilize a controlled vapor-phase potassium intercalation technique and identify a lightly doped stage, where the Raman modes of undoped and doped few-layer graphene flakes coexist. The spectra can be unambiguously distinguished from alkali doped graphite, and a modeling with the distribution of the layers yields an upper limit of flake thickness of five layers with a significant single-layer graphene content. Complementary statistical AFM measurements on individual few-layer graphene flakes find a consistent distribution of the layer numbers.
@article{arxiv.1807.09329,
title = {Incidence of multilayers in chemically exfoliated graphene},
author = {P. Szirmai and B. G. Márkus and J. C. Chacón-Torres and P. Eckerlein and K. Edelthalhammer and J. M. Englert and U. Mundloch and A. Hirsch and F. Hauke and B. Náfrádi and L. Forró and C. Kramberger and T. Pichler and F. Simon},
journal= {arXiv preprint arXiv:1807.09329},
year = {2020}
}