Visibility and Raman spectroscopy of mono and bilayer graphene on crystalline silicon

Abstract

Experimental studies of pristine graphene devices currently rely on the fact that the graphene crystallites can be visible under optical microscopes when the underlying substrate is engineered to exhibit high contrast. Here, we present that graphene can be visualized not only on a dielectric substrate but also on a crystalline Si surface of a silicon-on-insulator ͑SOI͒ wafer ͑SIMOX and Bonded͒ with thicknesses of Si ϳ70 nm and buried oxide ϳ140 nm, using monochromatic illumination. In addition, we have found that Raman spectroscopy shows similar features to standard graphene on SiO 2 substrates independent of the polarity of the Si surface. Finally, the Raman spectrum on SOI exhibits a higher intensity compared to that on bulk Si due to the interference enhancement effect of graphene on SOI. Thus, the usage of optical microscopy and Raman spectroscopy for detecting, locating, and characterizing graphene serves as a high throughput method to further study graphene on semiconductor systems and other substrates beyond SiO 2 / Si.

Ultrasensitive NO2 Sensor Based on Ohmic Metal–Semiconductor Interfaces of Electrolytically Exfoliated Graphene/Flame-Spray-Made SnO2 Nanoparticles Composite Operating at Low Temperatures

“…The graphene qualities after its incorporation into SnO 2 matrix may be evaluated from the peak intensity ratios of 2D to G ( I 2D / I G ) and D to G ( I D / I G ) as listed in the inset of Figure . I 2D / I G is in the range 0.35–0.43, indicating that the number of sp 2 layers is greater than 3 but still less than 10, , which is in agreement with the observed HR-TEM result. In addition, the values of I 2D / I G for P-0.5G and P-5G are similar but considerably higher than that of the graphene source, indicating that the average number of sp 2 layers of graphene in the composite is less than that of the graphene powder.…”

Optical identification of layered MoS2via the characteristic matrix method

“…9 According to this definition, the optical contrast of the monolayer graphene on SiO 2 /Si (Fig. 2(a)) can be written as 9,15,16…”

“…9 However, the Fresnel theory calculations become complicated and time-consuming when the number of layers of 2D materials is increased. 12,13,16 In this work, we demonstrate that the characteristic matrix method can be used to calculate the optical contrast of 2D layered MoS 2 on different substrates. By using this method, we obtained color contour plots of the optical contrast as a function of both the MoS 2 layer number and the incident light wavelength.…”

“…On the other hand, many theoretical calculations for the optical contrast of graphene, 9 MoS 2 , 12 and graphene/MoS 2 heterostructures 13 on SiO 2 /Si have been performed by using Fresnel theory. 9,[12][13][14][15][16][17] These studies provide a guide for the selection of the illumination wavelength or the substrates when observing the 2D materials using OM. 9 However, the Fresnel theory calculations become complicated and time-consuming when the number of layers of 2D materials is increased.…”

Graphene sheets embedded carbon film prepared by electron irradiation in electron cyclotron resonance plasma

“…This is the same with bilayer graphene 2D band, as reported by other researchers. [17][18][19] From theoretical study, these four peaks are due to the splitting of p and p* bands by the interaction of graphene layers. 15 Therefore, the four component bands illustrate the electronic structure of bilayer graphene, which determines its properties such as electrical conductivity and phonon emission.…”