Berlin 2018 – scientific programme
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DS: Fachverband Dünne Schichten
DS 28: 2D materials: Chalcogenides II (joint session HL/DS)
DS 28.6: Talk
Thursday, March 15, 2018, 10:45–11:00, A 151
Giant Gap-Plasmon Tip-Enhanced Raman Scattering of MoS2 Monolayers on Au Nanocluster Arrays — •Mahfujur Rahaman1, Alexander G. Milekhin2,3, E. E. Rodyakina2,3, A. V. Latyshev2,3, Volodymyr M. Dzhagan1,4, and Dietrich R.T. Zahn1 — 1Semiconductor Physics, Chemnitz University of Technology, D-09107, Chemnitz, Germany — 2Novosibirsk State University, Pirogov 2, 630090, Novosibirsk, Russia — 3Rzhanov Institute of Semiconductor Physics RAS, Lavrentiev Ave. 13, 630090, Novosibirsk, Russia — 4V. Lashkaryov Institute of Semiconductors Physics, Nat. Acad. of Sci. of Ukraine, 03028, Kyiv, Ukraine
We present the results on a gap-plasmon tip-enhanced Raman scattering study of MoS2 monolayers deposited on a periodic array of Au nanostructures on a silicon substrate forming a two dimensional (2D) crystal / plasmonic heterostructure. We observe a giant Raman enhancement of the phonon modes of the MoS2 monolayer located in a plasmonic gap between Au tip apex and Au nanoclusters. Tip-enhanced Raman (TER) mapping allowed us to determine the gap-plasmon field distribution responsible for the formation of hot spots. These hot spots provided an unprecedented giant Raman enhancement of 5.6 * 108 and a spatial resolution as small as 2.3 nm at ambient conditions. Moreover, due to strong hot electron doping in the order of 1.8 * 1013 cm-2, we observed a structural change of MoS2 from 2H to 1T phase. Thanks to the very good spatial resolution, we were able to spatially resolve those doping sites. Our results open the perspectives of optical diagnostics in nanoscale for many other 2D materials.