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Proceedings Paper

Optical signatures of defects in low temperature Raman and photoluminescence spectra of 2D crystals (Conference Presentation)
Author(s): Alexander A. Puretzky; Masoud Mahjouri-Samani; Xufan Li; Kai Xiao; Kai Wang; Juan Carlos Idrobo; Liangbo Liang; Bobby G. Sumpter; Mina Yoon; Vincent Meunier; David B. Geohegan
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Paper Abstract

Currently, two-dimensional (2D) layered materials are rapidly emerging as a new platform for many potential applications in nanoscale optoelectronics, optics, flexible electronics, energy, etc. Monolayers of 2D crystals [e.g., transition metals dichalcogenides (TMDs)] are basically surface and therefore, their optoelectronic properties are very sensitive to defects and environment including ambient gases and substrates. However, only limited number of studies is devoted to understanding of the effect of defects on their optical properties. It is not clear if the specific defects have their fingerprints in Raman, absorption, and PL spectra. Here, we report measurements of low temperature (4-150K) Raman and photoluminescence (PL) spectra of TMD monolayers (MoSe2, WS2) with variable and controlled concentrations of specific defects, i.e., chalcogenide atom vacancies, to reveal optical signatures of these defects. The defective TMD monolayers were synthesized using our new laser CVD approach. To identify the type of defects and their concentration the 2D crystals were transferred from a substrate to a TEM grid and atomic resolution STEM and EELS measurements were performed. Low temperature Raman and PL mapping were used to understand spatial distribution of the defects within the 2D crystals. The assignment of the observed spectral features in low temperature Raman and PL spectra was supported by ab initio theoretical modeling.

Synthesis science was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division. Characterization and computational science at CNMS was supported by the Scientific User Facilities Division, BES.

Paper Details

Date Published: 21 April 2017
PDF: 1 pages
Proc. SPIE 10093, Synthesis and Photonics of Nanoscale Materials XIV, 1009307 (21 April 2017); doi: 10.1117/12.2253363
Show Author Affiliations
Alexander A. Puretzky, Oak Ridge National Lab. (United States)
Masoud Mahjouri-Samani, Oak Ridge National Lab. (United States)
Xufan Li, Oak Ridge National Lab. (United States)
Kai Xiao, Oak Ridge National Lab. (United States)
Kai Wang, Oak Ridge National Lab. (United States)
Juan Carlos Idrobo, Oak Ridge National Lab. (United States)
Liangbo Liang, Oak Ridge National Lab. (United States)
Bobby G. Sumpter, Oak Ridge National Lab. (United States)
Mina Yoon, Oak Ridge National Lab. (United States)
Vincent Meunier, Rensselaer Polytechnic Institute (United States)
David B. Geohegan, Oak Ridge National Lab. (United States)


Published in SPIE Proceedings Vol. 10093:
Synthesis and Photonics of Nanoscale Materials XIV
David B. Geohegan; Jan J. Dubowski; Andrei V. Kabashin, Editor(s)

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