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Distinct photoluminescence and Raman spectroscopy signatures for identifying highly crystalline WS2 monolayers produced by different growth methods

Published online by Cambridge University Press:  08 March 2016

Amber McCreary ,
Ayse Berkdemir ,
Junjie Wang ,
Minh An Nguyen ,
Ana Laura Elías ,
Néstor Perea-López ,
Kazunori Fujisawa ,
Bernd Kabius ,
Victor Carozo  and
David A. Cullen
...Show all authors
Amber McCreary
Affiliation:
Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Ayse Berkdemir
Affiliation:
Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA; and Nanotechnology Research Center and Kayseri Vocational College, Erciyes University, Kayseri 38039, Turkey
Junjie Wang
Affiliation:
Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Minh An Nguyen
Affiliation:
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Ana Laura Elías
Affiliation:
Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Néstor Perea-López
Affiliation:
Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Kazunori Fujisawa
Affiliation:
Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Bernd Kabius
Affiliation:
Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Victor Carozo
Affiliation:
Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
David A. Cullen
Affiliation:
Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
Thomas E. Mallouk
Affiliation:
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
J. Zhu
Affiliation:
Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Mauricio Terrones*
Affiliation:
Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA; Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA; Department of Materials Science & Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA; and Research Center for Exotic Nanocarbons, Shinshu University, Nagano 380-8553, Japan
*
a) Address all correspondence to this author. e-mail: mut11@psu.edu
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Abstract

Transition metal dichalcogenides such as WS2 show exciting promise in electronic and optoelectronic applications. Significant variations in the transport, Raman, and photoluminescence (PL) can be found in the literature, yet it is rarely addressed why this is. In this report, Raman and PL of monolayered WS2 produced via different methods are studied and distinct features that indicate the degree of crystallinity of the material are observed. While the intensity of the LA(M) Raman mode is found to be a useful indicator to assess the crystallinity, PL is drastically more sensitive to the quality of the material than Raman spectroscopy. We also show that even exfoliated crystals, which are usually regarded as the most pristine material, can contain large amounts of defects that would not be apparent without Raman and PL measurements. These findings can be applied to the understanding of other two-dimensional heterostructured systems.

Keywords

Raman spectroscopyluminescencedefects

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Type
Invited Articles
Information
Journal of Materials Research , Volume 31 , Issue 7: Focus Issue: Two-Dimensional Heterostructure Materials , 14 April 2016 , pp. 931 - 944
Copyright
Copyright © Materials Research Society 2016 

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