Spectroscopic imaging ellipsometry for automated search of flakes of mono- and n-layers of 2D-materials

Abstract

Spectroscopic imaging ellipsometry (SIE) is used to localize and characterize flakes of conducting, semi-conducting and insulating 2D-materials. Although the research in the field of monolayers of 2D-materials increased the last years, it is still challenging to look for small flakes and distinguish between different layer numbers. Special substrates are used to enhance optical contrast for the conventional light microscopy (LM). In case when other functional support from the substrate is essential, an additional transfer step needs to be employed, bringing the drawbacks as contamination, cracking and wrinkling of the 2D materials. Furthermore it is time-consuming and not yet fully automatically to search for monolayers by contrast with the LM. Here we present a method, that is able to automatically localize regions with desired thicknesses, e.g. monolayers, of the different materials on arbitrary substrates.