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

• Published in: Journal of materials research Vol. 31; no. 7; pp. 931 - 944
• Main Authors: McCreary, Amber, Berkdemir, Ayse, Wang, Junjie, Nguyen, Minh An, Elías, Ana Laura, Perea-López, Néstor, Fujisawa, Kazunori, Kabius, Bernd, Carozo, Victor, Cullen, David A., Mallouk, Thomas E., Zhu, J., Terrones, Mauricio
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 14-04-2016; Springer International Publishing; Springer Nature B.V; Materials Research Society
• Subjects: Applied and Technical Physics; Biomaterials; Chemical vapor deposition; Crystals; defects; Editors; Energy; Graphene; Inorganic Chemistry; Invited Articles; Iodine; luminescence; Materials Engineering; Materials research; MATERIALS SCIENCE; Methods; Microscopy; Nanotechnology; Optical properties; Raman spectroscopy; Spectrum analysis; Sulfur; Thin films; Raman spectroscopy; luminescence; defects
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2016.47

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.