TY - JOUR

T1 - Giant gap-plasmon tip-enhanced Raman scattering of MoS2 monolayers on Au nanocluster arrays

AU - Milekhin, Alexander G.

AU - Rahaman, Mahfujur

AU - Rodyakina, Ekaterina E.

AU - Latyshev, Alexander V.

AU - Dzhagan, Volodymyr M.

AU - Zahn, Dietrich R.T.

N1 - Acknowledgements: The authors gratefully acknowledge financial support from Volkswagen Foundation, MERGE project (TU Chemnitz), State assignment (no. 0306-2016-0017), RFBR (project 18-02-00615_a), and the Ministry of Education and Science of the Russian Federation. The authors are thankful to Mr A. S. Medvedev for Au deposition. SEM studies and fabrication of metal nanostructures were performed using equipment of CCU “Nanostructures” at the Rzhanov Institute of Semiconductor Physics SB RAS.

PY - 2018/2/14

Y1 - 2018/2/14

N2 - In this article, we present the results of 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 in the MoS2 monolayer located in the plasmonic gap between the Au tip apex and Au nanoclusters. Tip-enhanced Raman mapping allows us to determine the gap-plasmon field distribution responsible for the formation of hot spots. These hot spots provide an unprecedented giant Raman enhancement of 5.6 × 108 and a spatial resolution as small as 2.3 nm under ambient conditions. Moreover, due to strong hot electron doping in the order of 1.8 × 1013 cm-2, we observe a structural change of MoS2 from the 2H to the 1T phase. Owing to the very good spatial resolution, we are able to spatially resolve those doping sites. To the best of our knowledge, this is the first time reporting of such a phenomenon with nm spatial resolution. Our results will open the perspectives of optical diagnostics with nanometer resolution for many other 2D materials.

AB - In this article, we present the results of 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 in the MoS2 monolayer located in the plasmonic gap between the Au tip apex and Au nanoclusters. Tip-enhanced Raman mapping allows us to determine the gap-plasmon field distribution responsible for the formation of hot spots. These hot spots provide an unprecedented giant Raman enhancement of 5.6 × 108 and a spatial resolution as small as 2.3 nm under ambient conditions. Moreover, due to strong hot electron doping in the order of 1.8 × 1013 cm-2, we observe a structural change of MoS2 from the 2H to the 1T phase. Owing to the very good spatial resolution, we are able to spatially resolve those doping sites. To the best of our knowledge, this is the first time reporting of such a phenomenon with nm spatial resolution. Our results will open the perspectives of optical diagnostics with nanometer resolution for many other 2D materials.

KW - TEMPERATURE-DEPENDENT RAMAN

KW - FEW-LAYER MOS2

KW - THERMAL-CONDUCTIVITY

KW - FIELD DISTRIBUTION

KW - LOCALIZED STRAIN

KW - SINGLE-MOLECULE

KW - SPECTROSCOPY

KW - NANOSCALE

KW - MICROSCOPY

KW - PHOTOLUMINESCENCE

UR - http://www.scopus.com/inward/record.url?scp=85041829683&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/e97759b4-ea1e-31c0-bdb6-cfc1e57d4db6/

U2 - 10.1039/c7nr06640f

DO - 10.1039/c7nr06640f

M3 - Article

C2 - 29308796

AN - SCOPUS:85041829683

VL - 10

SP - 2755

EP - 2763

JO - Nanoscale

JF - Nanoscale

SN - 2040-3364

IS - 6

ER -