Raman analysis of gold on WSe₂ single crystal film

RETRACTED: Artificial Intelligence Algorithm Enabled Industrial-Scale Graphene Characterization

“…Among many graphene synthesis routes, CVD is chosen in this work due to its high-quality, low-cost, and scalability to mass production for industrial applications [22][23][24]. Furthermore, among many characterization methods, Raman analysis is chosen in this work because it is a popular, versatile, high-throughput, very low invasive, and non-destructive methodology for the characterization of graphene [25][26][27][28]. Probing graphene quality by Raman spectroscopy is now a straightforward and automated process, applicable at both laboratory and mass-production scales, which involves simple sample preparation, a laser-based microscopy, and ambient operation.…”

“…Surprisingly, the 2LG region that appeared to be uniform under an optical microscope shows at least two distinct divisions in the Raman map of I2D/IG ( Figure 3F), indicating that the 2LG region was made of at least two domains with very different stacking orders (i.e., twisting angles). Although Raman mapping is a useful tool for researchers to effectively estimate the quality of a graphene sample [25][26][27][28][29][30][31][32][33], it is not an efficient methodology for industrial manufacturers who need the quality inspection of a centimeter-scale graphene film to be completed within a minute for As for the graphene sample grown on bare Cu, Raman spectra taken from the four spots indicated in Figure 3D all had different ω G , ω 2D , I 2D /I G , and Γ 2D ( Figure 3E). Based on the Raman spectra characteristics, spots 1 and 4 were found to be 1LG and 3LG, respectively, while spots 2 and 3 were found to be 2LG regions since they had the same optical contrast under optical microscope, and their optical contrast is intermediate between that of 1LG and that of 3LG (see Figure 3D).…”

Determining optical constants of 2D materials with neural networks from multi-angle reflectometry data

“…Previously, we have carried out both theoretical and experimental studies on various types of 2D materials including graphene [18], monolayers of MoS 2 [15,16] and WSe 2 [17]. For example in [15], we develop a numerical method to extract the refractive index of monolayer MoS 2 that are synthesized on quartz and silicon substrates with CVD.…”

“…In 2004, Novoselov et al experimentally showed that 2D atomic crystals of carbon could be obtained with a top-down exfoliation technique [13]. Later we have learned that other types of materials, such as transition metal dichalcogenides, metal oxides, and boron nitride can be obtained in the monolayer or a-few layers form [14][15][16][17].…”

“…In terms of device design and realization, precise knowledge of optical and electrical properties is a must and accurate methods are needed to extract these properties. However, 2D materials exhibit another important feature: their optical properties change with wavelength, temperature, doping, and external factors such as applied gate voltage and magnetic fields [15][16][17][18]. Each time one or more of these parameters change, the refractive index changes.…”