Thickness determination of MoS2, MoSe2, WS2 and WSe2 on transparent stamps used for deterministic transfer of 2D materials

• Published in: Nano research Vol. 12; no. 7; pp. 1691 - 1695
• Main Authors: Taghavi, Najme S., Gant, Patricia, Huang, Peng, Niehues, Iris, Schmidt, Robert, Michaelis de Vasconcellos, Steffen, Bratschitsch, Rudolf, García-Hernández, Mar, Frisenda, Riccardo, Castellanos-Gomez, Andres
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01-07-2019; Springer Nature B.V
• Subjects: Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Chemistry and Materials Science; Condensed Matter Physics; Dependence; Flakes; Image transmission; Light microscopy; Materials Science; Microscopes; Microscopy; Molybdenum compounds; Molybdenum disulfide; Nanotechnology; Optical microscopy; Research Article; Substrates; Thickness; Transition metal compounds; Tungsten disulfide; Two dimensional analysis; Two dimensional materials; transparent substrate; trasmittance; transition metal dichalcogenides; optical identification
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-019-2424-6

Here, we propose a method to determine the thickness of the most common transition metal dichalcogenides (TMDCs) placed on the surface of transparent stamps, used for the deterministic placement of two-dimensional materials, by analyzing the red, green and blue channels of transmission-mode optical microscopy images of the samples. In particular, the blue channel transmittance shows a large and monotonic thickness dependence, making it a very convenient probe of the flake thickness. The method proves to be robust given the small flake-to-flake variation and the insensitivity to doping changes of MoS
2
. We also tested the method for MoSe
2
, WS
2
and WSe
2
. These results provide a reference guide to identify the number of layers of this family of materials on transparent substrates only using optical microscopy.