npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041
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Article

Research Paper

New Phys.: Sae Mulli 2020; 70: 535-538

Published online June 30, 2020 https://doi.org/10.3938/NPSM.70.535

Copyright © New Physics: Sae Mulli.

Optical Properties of 2H Phase WTe$_{2}$ Flakes

Yonghee JO1, Dae Hyun JUNG1, TaeWan KIM1*, ChaeHo SHIN2

1Department of Electrical Engineering and Smart Grid Research Center, Jeonbuk National University, Jeonju 54896, Korea
2Division of Industrial Metrology, Korea Research Institute of Standards and Science, Daejeon 34113, Korea

Correspondence to:twkim@jbnu.ac.kr

Received: March 3, 2020; Revised: April 28, 2020; Accepted: May 4, 2020

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Tungsten ditelluride (WTe$_{2}$) has attracted increasing attention because of its unique properties, such as its relatively narrow bandgap and large carrier transport, which depend on its phases. A mechanically exfoliated ultrathin WTe$_{2}$ flake was transferred on to a SiO$_{2}$/Si substrate. A transferred WTe$_{2}$ flake with a thickness of 10 -- 40 nm was determined by using Atomic force microscopy (AFM). We systematically investigated the thickness-dependent optical properties of the WTe$_{2}$ flakes. The dominant Raman $\mathbf{A}_{1}^{3}, \mathbf{A}_{1}^{4}, \mathbf{A}_{1}^{7} and \mathbf{A}_{1}^{9}$ peaks were observed. Strong photoluminescence emission peaks with a band gap of 1.83 eV were observed for flakes with thicknesses of 10 nm, possibly because of a radiative transition. We note that the radiative transition efficiency was enhanced with decreasing number of WTe$_{2}$ flake layers.

Keywords: TMDs, WTe$_{2}$, Raman spectroscopy, Photoluminescence

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