Investigation of multilayer domains in large-scale CVD monolayer graphene by optical imaging

Abstract

CVD graphene is a promising candidate for optoelectronic applications due to its high quality and high yield. However, multi-layer domains could inevitably form at the nucleation centers during the growth. Here, we propose an optical imaging technique to precisely identify the multilayer domains and also the ratio of their coverage in large-scale CVD monolayer graphene. We have also shown that the stacking disorder in twisted bilayer graphene as well as the impurities on the graphene surface could be distinguished by optical imaging. Finally, we investigated the effects of bilayer domains on the optical and electrical properties of CVD graphene, and found that the carrier mobility of CVD graphene is seriously limited by scattering from bilayer domains. Our results could be useful for guiding future optoelectronic applications of large-scale CVD graphene.

Layer-number dependent and structural defect related optical properties of InSe

“…A microscope was used to obtain optical images of the samples and Matlab soware was utilized to read out the red (R), green (G), blue (B) values at each pixel of the optical images and get the histogram of optical contrast distribution. 29 Atomic force microscope (AFM) was employed to conrm the thickness of InSe akes. Raman and PL spectra were collected using a LabRAM HR800 Raman system (excitation wavelength ¼ 532 nm).…”

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

“…Mechanical exfoliation, nonetheless, yields randomly distributed flakes of various thicknesses and sizes on the surface of the substrate. This limitation has been overcome to a great extent through the development of rapid methods to find and identify thin flakes based on the observation of the apparent color when they are transferred onto a SiO2/Si surface [6][7][8][9][10][11][12]. On this substrate, there is a dependency of the apparent color of the flake with its thickness due to thin-film interference effects and many epi-illumination (reflection mode) microscopy-based methods have been developed to identify 2D materials and to determine their number of layers [6][7][8][9][10][11][12].…”

“…epi-illumination (reflection mode) microscopy-based methods have been developed to identify 2D materials and to determine their number of layers [6][7][8][9][10][11][12]. An alternative way to overcome the limitations of mechanical exfoliation relies on the use of experimental tools that allow for the deterministic placement of flakes onto any desired sample position with micrometer accuracy [13][14][15][16][17][18][19].…”

Graphene Grown on Ni Foam: Molecular Sensing, Graphene-Enhanced Raman Scattering, and Galvanic Exchange for Surface-Enhanced Raman Scattering Applications

“…24 This configuration is particularly interesting since the weak interaction between layers allows high charge carrier mobility as well as interesting optical properties such as absorption bands in the visible range. 48,49,50 Page 10 of 35…”