Raman spectroscopy regulation in van der Waals crystals
Raman spectroscopy is a versatile tool widely used for comprehensive probing of crystal information. However, generally when applied in narrow-band-gap van der Waals crystals, it is liable to form a “bug,” especially in transition-metal-dichalcogenides (TMDs). That is, several resonant Raman-scattering (RS) modes will inevitably appear in the Raman spectra with strong intensity, interfering with the desired signal of optical-phonon modes. Here, we propose cross-sectional polarized Raman scattering capable of regulating the intensity of RS modes in accordance with quasi-sinusoidal rules. Typically, for MoS2 and WS2, when the polarization vector of excited light is along the c axis of the crystal, all RS modes are nearly completely “expunged” from the Raman spectra. The mechanism is that the absorption of most TMDs with a space group of R3m for the light polarized along the c axis is infinitesimal, thus forming a small coupling intensity of electronic states excited optically and acoustic-phonon modes at point M, which in turn restrain the appearance of RS modes. The regulating strategy proposed can be applied to other van der Waals crystals so as to obtain a high signal-to-noise ratio Raman spectrum.
基金项目：National Natural Science Foundation of China (NSFC)10.13039/501100001809 (61427901, 61604178, 91333207, U1505252).
Yanming Zhu：State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
Fadi Li：Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Feng Huang：State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
【1】F. Xia, H. Wang, D. Xiao, M. Dubey, and A. Ramasubramaniam, “Two-dimensional material nanophotonics,” Nat. Photonics 8 , 899–907 (2014).
【2】Y. Gong, J. Lin, X. Wang, G. Shi, S. Lei, Z. Lin, X. Zou, G. Ye, R. Vajtai, B. I. Yakobson, H. Terrones, M. Terrones, B. K. Tay, J. Lou, S. T. Pantelides, Z. Liu, W. Zhou, and P. M. Ajayan, “Vertical and in-plane heterostructures from WS2/MoS2 monolayers,” Nat. Mater. 13 , 1135–1142 (2014).
【3】Q. H. Wang, K. Kalantar-Zadeh, A. Kis, J. N. Coleman, and M. S. Strano, “Electronics and optoelectronics of two-dimensional transition metal dichalcogenides,” Nat. Nanotechnol. 7 , 699–712 (2012).
【4】W. Zheng, R. Lin, J. Ran, Z. Zhang, X. Ji, and F. Huang, “Vacuum-ultraviolet photovoltaic detector,” ACS Nano 12 , 425–431 (2018).
【5】A. K. Geim, and I. V. Grigorieva, “Van der Waals heterostructures,” Nature 499 , 419–425 (2013).
【6】W. Zheng, Z. Zhang, R. Lin, K. Xu, J. He, and F. Huang, “High-crystalline 2D layered PbI2 with ultrasmooth surface: liquid-phase synthesis and application of high-speed photon detection,” Adv. Electron. Mater. 2 , 1600291 (2016).
【7】M. P. Levendorf, C.-J. Kim, L. Brown, P. Y. Huang, R. W. Havener, D. A. Muller, and J. Park, “Graphene and boron nitride lateral heterostructures for atomically thin circuitry,” Nature 488 , 627–632 (2012).
【8】X. Zhang, X.-F. Qiao, W. Shi, J.-B. Wu, D.-S. Jiang, and P.-H. Tan, “Phonon and Raman scattering of two-dimensional transition metal dichalcogenides from monolayer, multilayer to bulk material,” Chem. Soc. Rev. 44 , 2757–2785 (2015).
【9】A. Berkdemir, H. R. Gutiérrez, A. R. Botello-Méndez, N. Perea-López, A. L. Elías, C.-I. Chia, B. Wang, V. H. Crespi, F. López-Urías, J.-C. Charlier, H. Terrones, and M. Terrones, “Identification of individual and few layers of WS2 using Raman spectroscopy,” Sci. Rep. 3 , 1755 (2013).
【10】A. C. Ferrari, and D. M. Basko, “Raman spectroscopy as a versatile tool for studying the properties of graphene,” Nat. Nanotechnol. 8 , 235–246 (2013).
【11】H. Li, Q. Zhang, C. C. R. Yap, B. K. Tay, T. H. T. Edwin, A. Olivier, and D. Baillargeat, “From bulk to monolayer MoS2: evolution of Raman scattering,” Adv. Funct. Mater. 22 , 1385–1390 (2012).
【12】A. C. Ferrari, J. C. Meyer, V. Scardaci, C. Casiraghi, M. Lazzeri, F. Mauri, S. Piscanec, D. Jiang, K. S. Novoselov, S. Roth, and A. K. Geim, “Raman spectrum of graphene and graphene layers,” Phys. Rev. Lett. 97 , 187401 (2006).
【13】C. Casiraghi, A. Hartschuh, H. Qian, S. Piscanec, C. Georgi, A. Fasoli, K. S. Novoselov, D. M. Basko, and A. C. Ferrari, “Raman spectroscopy of graphene edges,” Nano Lett. 9 , 1433–1441 (2009).
【14】K. Go asa, M. Grzeszczyk, P. Leszczyński, C. Faugeras, A. A. L. Nicolet, A. Wysmo ek, M. Potemski, and A. Babiński, “Multiphonon resonant Raman scattering in MoS2,” Appl. Phys. Lett. 104 , 092106 (2014).
【15】A. A. Mitioglu, P. Plochocka, G. Deligeorgis, S. Anghel, L. Kulyuk, and D. K. Maude, “Second-order resonant Raman scattering in single-layer tungsten disulfide WS2,” Phys. Rev. B 89 , 245442 (2014).
【16】G. L. Frey, R. Tenne, M. J. Matthews, M. S. Dresselhaus, and G. Dresselhaus, “Raman and resonance Raman investigation of MoS2 nanoparticles,” Phys. Rev. B 60 , 2883–2892 (1999).
【17】K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, “Atomically thin MoS2: a new direct-gap semiconductor,” Phys. Rev. Lett. 105 , 136805 (2010).
【18】W. Zhao, Z. Ghorannevis, L. Chu, M. Toh, C. Kloc, P.-H. Tan, and G. Eda, “Evolution of electronic structure in atomically thin sheets of WS2 and WSe2,” ACS Nano 7 , 791–797 (2013).
【19】A. C. Ferrari, “Raman spectroscopy of graphene and graphite: disorder, electron-phonon coupling, doping and nonadiabatic effects,” Solid State Commun. 143 , 47–57 (2007).
【20】L. G. Cancado, A. Jorio, E. H. Martins Ferreira, F. Stavale, C. A. Achete, R. B. Capaz, M. V. O. Moutinho, A. Lombardo, T. S. Kulmala, and A. C. Ferrari, “Quantifying defects in graphene via Raman spectroscopy at different excitation energies,” Nano Lett. 11 , 3190–3196 (2011).
【21】J. P. Perdew, K. Burke, and M. Ernzerhof, “Generalized gradient approximation made simple,” Phys. Rev. Lett. 77 , 3865–3868 (1996).
【22】W. Zheng, F. Li, G. Li, Y. Liang, X. Ji, F. Yang, Z. Zhang, and F. Huang, “Laser tuning in van der Waals crystals,” ACS Nano 12 , 2001–2007 (2018).
【23】J. Kang, S. Tongay, J. Zhou, J. Li, and J. Wu, “Band offsets and heterostructures of two-dimensional semiconductors,” Appl. Phys. Lett. 102 , 012111 (2013).
【24】M. Cardona, and G. Guntherodt, Light Scattering in Solids II (Springer, 1982).
【25】W. Zheng, R. Zheng, F. Huang, H. Wu, and F. Li, “Raman tensor of AlN bulk single crystal,” Photon. Res. 3 , 38–43 (2015).
【26】C. Kranert, C. Sturm, R. Schmidt-Grund, and M. Grundmann, “Raman tensor formalism for optically anisotropic crystals,” Phys. Rev. Lett. 116 , 127401 (2016).
【27】C. Kranert, C. Sturm, R. Schmidt-Grund, and M. Grundmann, “Raman tensor elements of β-Ga2O3,” Sci. Rep. 6 , 35964 (2016).
【28】W. Zheng, J. Yan, F. Li, and F. Huang, “Elucidation of ‘phase difference’ in Raman tensor formalism,” Photon. Res. 6 , 709–712 (2018).
【29】H. J. Monkhorst, and J. D. Pack, “Special points for Brillouin-zone integrations,” Phys. Rev. B 13 , 5188–5192 (1976).
【30】S. M. Heald, and E. A. Stern, “Anisotropic X-ray absorption in layered compounds,” Phys. Rev. B 16 , 5549–5559 (1977).
Wei Zheng, Yanming Zhu, Fadi Li, and Feng Huang, "Raman spectroscopy regulation in van der Waals crystals," Photonics Research 6(11), 991-995 (2018)