Thickness determination of MoS2, MoSe2, WS2 and WSe2 on transparent stamps used for deterministic transfer of 2D materials
transition metal dichalcogenides, optical identification, transparent substrate, trasmittance
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 MoS2. We also tested the method for MoSe2, WS2 and WSe2. These results provide a reference guide to identify the number of layers of this family of materials on transparent substrates only using optical microscopy.
Tsinghua University Press
Najme S. Taghavi,Patricia Gant,Peng Huang,Iris Niehues,Robert Schmidt,Steffen Michaelis de Vasconcellos,Rudolf Bratschitsch,Mar García-Hernández,Riccardo Frisenda,Andres Castellanos-Gomez, Thickness determination of MoS2, MoSe2, WS2 and WSe2 on transparent stamps used for deterministic transfer of 2D materials. NanoRes.2019, 12(7): 1691–1695