Transition metal dichalcogenides (TMDCs) have attracted significant attention for optoelectronic, photovoltaic and photoelectrochemical applications. The properties of TMDCs are highly dependent on the number of stacked atomic layers, which is usually counted post-fabrication, using a combination of optical methods and atomic force microscopy (AFM) height measurements. Here, we use photoluminescence spectroscopy and three different AFM methods to demonstrate significant discrepancies in height measurements of exfoliated MoSe2 flakes on SiO2 depending on the method used. We highlight that overlooking effects from electrostatic forces, contaminants and surface binding can be misleading when measuring the height of a MoSe2 flake. These factors must be taken into account as a part of the protocol for counting TMDC layers.
@article{arxiv.2109.05354,
title = {How high is a MoSe$_2$ monolayer?},
author = {Rikke Plougmann and Megan Cowie and Yacine Benkirane and Léonard Schué and Zeno Schumacher and Peter Grütter},
journal= {arXiv preprint arXiv:2109.05354},
year = {2021}
}