Graphical Abstract
![](https://wqketang.oss-cn-beijing.aliyuncs.com/zip-unzip/zip-8cd3e3cc-9ee7-45fe-9b94-6ddac8bb3299/nr-11-12-6316/files/nr-11-12-6316-FE1.jpg?Expires=1725758181&OSSAccessKeyId=STS.NT5eViCkqzTYdbfdqxMkjpyyq&Signature=75zmFT1HbuDI6eme6nAMBnBJuNM%3D&security-token=CAISywJ1q6Ft5B2yfSjIr5eALuzdrrRQzZayZkTXgHEtQeRGn7zSkzz2IHtKenhsBOsbtfk1mG5W5%2FgZlqJ9SptIAEfJa9d99MzUP%2FpFltCT1fau5Jko1beHewHKeTOZsebWZ%2BLmNqC%2FHt6md1HDkAJq3LL%2Bbk%2FMdle5MJqP%2B%2FUFB5ZtKWveVzddA8pMLQZPsdITMWCrVcygKRn3mGHdfiEK00he8TouufTinpHMskGA1Aell7Mvyt6vcsT%2BXa5FJ4xiVtq55utye5fa3TRYgxowr%2Fwo0v0YpGya5YzHXwcPskvdKZbo78UqLQlla6w%2BGqFJqvPxr%2Fp8t%2Fx5fWJKAezhVgs8cVM8JOjIqKOscIsiJsO71SmqFV55c8Fdm%2BgUooJVgIMhTnduUfAPJAGOxzJitP%2BUVGGphr60TEnBL4rB5MUctfzRp75SXVPUTzDnGoABjuNLcf76FQN6p3t%2BSlCg%2FxR5C72RIk78k%2BUi44L9ZBmFT6F8GV7aXA52D1Ps56knKF6PAnhRivwyTxgsolycBfvccb3t5jGJ24SgY0aYosAECutxAo7sJhSwlwZvGwGDZJsop1vGiZ8eN1MbtZeRRuMeaZ2I%2BQo%2BnVP6Cf%2F0pDsgAA%3D%3D)
Discover the SciOpen Platform and Achieve Your Research Goals with Ease.
Two-dimensional (2D) materials and their heterostructures, with wafer-scale synthesis methods and fascinating properties, have attracted significant interest and triggered revolutions in corresponding device applications. However, facile methods to realize accurate, intelligent, and large-area characterizations of these 2D nanostructures are still highly desired. Herein, we report the successful application of machine-learning strategy in the optical identification of 2D nanostructures. The machine-learning optical identification (MOI) method endows optical microscopy with intelligent insight into the characteristic color information of 2D nanostructures in the optical photograph. The experimental results indicate that the MOI method enables accurate, intelligent, and large-area characterizations of graphene, molybdenum disulfide, and their heterostructures, including identifications of the thickness, existence of impurities, and even stacking order. With the convergence of artificial intelligence and nanoscience, this intelligent identification method can certainly promote fundamental research and wafer-scale device applications of 2D nanostructures.
Das Sarma, S.; Adam, S.; Hwang, E. H.; Rossi, E. Electronic transport in two-dimensional graphene. Rev. Mod. Phys. 2011, 83, 407–470.
Geim, A. K.; Novoselov, K. S. The rise of graphene. Nat. Mater. 2007, 6, 183–191.
Lin, X. Y.; Su, L.; Si, Z. Z.; Zhang, Y. G.; Bournel, A.; Zhang, Y.; Klein, J. O.; Fert, A.; Zhao, W. S. Gate-driven pure spin current in graphene. Phys. Rev. Appl. 2017, 8, 034006.
Novoselov, K. S.; Mishchenko, A.; Carvalho, A.; Castro Neto, A. H. 2D materials and van der Waals heterostructures. Science 2016, 353, aac9439.
Xia, F. N.; Wang, H.; Xiao, D.; Dubey, M.; Ramasubramaniam, A. Two-dimensional material nanophotonics. Nat. Photonics 2014, 8, 899–907.
Geim, A. K.; Grigorieva, I. V. Van der Waals heterostructures. Nature 2013, 499, 419–425.
Zhang, Z. W.; Chen, P.; Duan, X. D.; Zang, K. T.; Luo, J.; Duan, X. F. Robust epitaxial growth of two-dimensional heterostructures, multiheterostructures, and superlattices. Science 2017, 357, 788–792.
Wu, T. R.; Zhang, X. F.; Yuan, Q. H.; Xue, J. C.; Lu, G. Y.; Liu, Z. H.; Wang, H. S.; Wang, H. M.; Ding, F.; Yu, Q. K. et al. Fast growth of inch-sized single-crystalline graphene from a controlled single nucleus on Cu-Ni alloys. Nat. Mater. 2015, 15, 43–47.
Xu, X. Z.; Zhang, Z. H.; Dong, J. C.; Yi, D.; Niu, J. J.; Wu, M. H.; Lin, L.; Yin, R. K.; Li, M. Q.; Zhou, J. Y. et al. Ultrafast epitaxial growth of metre-sized single-crystal graphene on industrial Cu foil. Sci. Bull. 2017, 62, 1074–1080.
Lee, J. H.; Lee, E. K.; Joo, W. J.; Jang, Y.; Kim, B. S.; Lim, J. Y.; Choi, S. H.; Ahn, S. J.; Ahn, J. R.; Park, M. H. et al. Wafer-scale growth of single-crystal monolayer graphene on reusable hydrogen-terminated germanium. Science 2014, 344, 286–289.
Huang, P. Y.; Ruiz-Vargas, C. S.; van der Zande, A. M.; Whitney, W. S.; Levendorf, M. P.; Kevek, J. W.; Garg, S.; Alden, J. S.; Hustedt, C. J.; Zhu, Y. et al. Grains and grain boundaries in single-layer graphene atomic patchwork quilts. Nature 2011, 469, 389–392.
Meyer, J. C.; Geim, A. K.; Katsnelson, M. I.; Novoselov, K. S.; Booth, T. J.; Roth, S. The structure of suspended graphene sheets. Nature 2007, 446, 60–63.
Zhao, W.; Xia, B. Y.; Lin, L.; Xiao, X. Y.; Liu, P.; Lin, X. Y.; Peng, H. L.; Zhu, Y. M.; Yu, R.; Lei, P. et al. Low-energy transmission electron diffraction and imaging of large-area graphene. Sci. Adv. 2017, 3, e1603231.
Zhang, Y. B.; Tang, T. T.; Girit, C.; Hao, Z.; Martin, M. C.; Zettl, A.; Crommie, M. F.; Shen, Y. R.; Wang, F. Direct observation of a widely tunable bandgap in bilayer graphene. Nature 2009, 459, 820–823.
Wastl, D. S.; Weymouth, A. J.; Giessibl, F. J. Atomically resolved graphitic surfaces in air by atomic force microscopy. ACS Nano 2014, 8, 5233–5239.
Tu, Q.; Lange, B.; Parlak, Z.; Lopes, J. M. J.; Blum, V.; Zauscher, S. Quantitative subsurface atomic structure fingerprint for 2D materials and heterostructures by firstprinciples-calibrated contact-resonance atomic force microscopy. ACS Nano 2016, 10, 6491–6500.
Ferrari, A. C.; Basko, D. M. Raman spectroscopy as a versatile tool for studying the properties of graphene. Nat. Nanotechnol. 2013, 8, 235–246.
Duong, D. L.; Han, G. H.; Lee, S. M.; Gunes, F.; Kim, E. S.; Kim, S. T.; Kim, H.; Ta, Q. H.; So, K. P.; Yoon, S. J. et al. Probing graphene grain boundaries with optical microscopy. Nature 2012, 490, 235–239.
Li, H.; Wu, J.; Huang, X.; Lu, G.; Yang, J.; Lu, X.; Xiong, Q. H.; Zhang, H. Rapid and reliable thickness identification of two-dimensional nanosheets using optical microscopy. ACS Nano 2013, 7, 10344–10353.
Li, W.; Moon, S.; Wojcik, M.; Xu, K. Direct optical visualization of graphene and its nanoscale defects on transparent substrates. Nano Lett. 2016, 16, 5027–5031.
Blake, P.; Hill, E. W.; Neto, A. H. C.; Novoselov, K. S.; Jiang, D.; Yang, R.; Booth, T. J.; Geim, A. K. Making graphene visible. Appl. Phys. Lett. 2007, 91, 063124.
Ni, Z. H.; Wang, H. M.; Kasim, J.; Fan, H. M.; Yu, T.; Wu, Y. H.; Feng, Y. P.; Shen, Z. X. Graphene thickness determination using reflection and contrast spectroscopy. Nano Lett. 2007, 7, 2758–2763.
Li, X. S.; Cai, W. W.; An, J. H.; Kim, S.; Nah, J.; Yang, D. X.; Piner, R.; Velamakanni, A.; Jung, I.; Tutuc, E. et al. Large-area synthesis of high-quality and uniform graphene films on copper foils. Science 2009, 324, 1312–1314.
Reina, A.; Jia, X. T.; Ho, J.; Nezich, D.; Son, H.; Bulovic, V.; Dresselhaus, M. S.; Kong, J. Large area, few-layer graphene films on arbitrary substrates by chemical vapor deposition. Nano Lett. 2009, 9, 30–35.
Lee, Y.; Lee, J.; Bark, H.; Oh, I.; Ryu, G. H.; Lee, Z.; Kim, H.; Cho, J. H.; Ahn, J.; Lee, C. Synthesis of wafer-scale uniform molybdenum disulfide films with control over the layer number using a gas phase sulfur precursor. Nanoscale 2014, 6, 2821–2826.
Zhao, M.; Ye, Y.; Han, Y. M.; Xia, Y.; Zhu, H. Y.; Wang, S. Q.; Wang, Y.; Muller, D. A.; Zhang, X. Large-scale chemical assembly of atomically thin transistors and circuits. Nat. Nanotechnol. 2016, 11, 954–959.
Alexeev, E. M.; Catanzaro, A.; Skrypka, O. V.; Nayak, P. K.; Ahn, S.; Pak, S.; Lee, J.; Sohn, J. I.; Novoselov, K. S.; Shin, H. S. et al. Imaging of interlayer coupling in van der Waals heterostructures using a bright-field optical microscope. Nano Lett. 2017, 17, 5342–5349.
Tan, Y.; Liu, X. B.; He, Z. L.; Liu, Y. R.; Zhao, M. W.; Zhang, H.; Chen, F. Tuning of interlayer coupling in largearea graphene/WSe2 van der Waals heterostructure via ion irradiation: Optical evidences and photonic applications. ACS Photonics 2017, 4, 1531–1538.
Nolen, C. M.; Denina, G.; Teweldebrhan, D.; Bhanu, B.; Balandin, A. A. High-throughput large-area automated identification and quality control of graphene and few-layer graphene films. ACS Nano 2011, 5, 914–922.
Maxmen, A. Deep learning sharpens views of cells and genes. Nature 2018, 553, 9–10.
Christmann, A.; Steinwart, I. Support Vector Machines; Springer-Verlag: New York, 2008; pp 613.
Castellanos-Gomez, A.; Agraït, N.; Rubio-Bollinger, G. Optical identification of atomically thin dichalcogenide crystals. Appl. Phys. Lett. 2010, 96, 213116.
Zhu, F.; Lin, X. Y.; Liu, P.; Jiang, K. L.; Wei, Y.; Wu, Y.; Wang, J. P.; Fan, S. S. Heating graphene to incandescence and the measurement of its work function by thermionic emission method. Nano Res. 2014, 7, 553–560.
Castro Neto, A. H.; Guinea, F.; Peres, N. M. R.; Novoselov, K. S.; Geim, A. K. The electronic properties of graphene. Rev. Mod. Phys. 2009, 81, 109–162.
Lu, Z. X.; Sun, L. F.; Xu, G. C.; Zheng, J. Y.; Zhang, Q.; Wang, J. Y.; Jiao, L. Y. Universal transfer and stacking of chemical vapor deposition grown two-dimensional atomic layers with water-soluble polymer mediator. ACS Nano 2016, 10, 5237–5242.
Knittl, Z. Optics of Thin Films: An Optical Multilayer Theory; Wiley: London, 1976; pp 548.
Zhang, H.; Ma, Y. G.; Wan, Y.; Rong, X.; Xie, Z. A.; Wang, W.; Dai, L. Measuring the refractive index of highly crystalline monolayer MoS2 with high confidence. Sci. Rep. 2015, 5, 8440.
Palik, E. D. Handbook of Optical Constants of Solids; Elsevier: Amsterdam, 1997.
Masubuchi, S.; Morimoto, M.; Morikawa, S.; Onodera, M.; Asakawa, Y.; Watanabe, K.; Taniguchi, T.; Machida, T. Autonomous robotic searching and assembly of two-dimensional crystals to build van der Waals superlattices. Nat. Commun. 2018, 9, 1413.
Novoselov, K. S.; Geim, A. K.; Morozov, S. V.; Jiang, D.; Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A. A. Electric field effect in atomically thin carbon films. Science 2004, 306, 666–669.