Antony, Vidhu Catherine — Analysis of the Optical Visibility of Graphite on different substrates and Van-der-Waals Hetero-structures

The marked visibility of graphene is due to the phase shift in the interference colour. The study is based on the analysis of graphene visibility on various substrates and hetero-structures such as transition metal dichalcogenides (TMDCs) like Molybdenum Disulphide (MoS2) and hexagonal Boron Nitrite (h-BN). The visibility of graphene depends on the type of substrate, the thickness of the graphite layer, the thickness of various layers of the substrate and the incident wavelength. A comparison of the theoretically obtained contrast colour plots for each of the particular instances with the experimental images was made. The contrast of the graphite layer on the substrate was then calculated to figure out at which wavelength range it is best visible.

References :

[1] Roman V Gorbachev, Ibtsam Riaz, Rahul R Nair, Rashid Jalil, Liam Britnell, Branson D Belle, Ernie W Hill, Kostya S Novoselov, Kenji Watanabe, Takashi Taniguchi, et al. Hunting for monolayer boron nitride: optical and raman signatures. Small, 7(4): 465-468,2011.

[2] IH Malitson. Interspecimen comparison of the refractive index of fused silica. Josa, 55(10): 1205-1209,1965.

[3] Edward D Palik. Handbook of Optical Constants of Solids. Academic Press, 1998.

[4] Eli Peli. Contrast in complex images. JOSA A, 7(10): 2032-2040,1990.

[5] MicroChem NANOTM PMMA. Copolymer datasheet. MICROCHEM Polymers, 2011 .

[6] S Roddaro, P Pingue, V Piazza, V Pellegrini, and F Beltram. The optical visibility of graphene: interference colors of ultrathin graphite on sio2. Nano letters, 7(9): 2707-2710,2007.

[7] Nihit Saigal, Amlan Mukherjee, Vasam Sugunakar, and Sandip Ghosh. Angle of incidence averaging in reflectance measurements with optical microscopes for studying layered two-dimensional materials. Review of Scientific Instruments, 85(7): 073105,2014.

[8] N Sultanova, S Kasarova, and I Nikolov. Dispersion properties of optical polymers. Acta Physica Polonica-Series A General Physics, 116(4): 585,2009.

[9] Berge Tatian. Fitting refractive-index data with the sellmeier dispersion formula. Applied optics, 23(24): 4477-4485, 1984 .

[10] Ying Ying Wang, Ren Xi Gao, Zhen Hua Ni, Hui He, Shu Peng Guo, Huan Ping Yang, Chun Xiao Cong, and Ting Yu. Thickness identification of two-dimensional materials by optical imaging. Nanotechnology, 23(49): 495713,2012.

[11] Hui Zhang, Yaoguang Ma, Yi Wan, Xin Rong, Ziang Xie, Wei Wang, and Lun Dai. Measuring the refractive index of highly crystalline monolayer mos2 with high confidence. Scientific reports, 5,2015 .