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Research Article

Reliable and broad-range layer identification of Au-assisted exfoliated large area MoS2 and WS2 using reflection spectroscopic fingerprints

Bo Zou1, Yu Zhou1, Yan Zhou2, Yanyan Wu1, Yang He1, Xiaonan Wang1, Jinfeng Yang1, Lianghui Zhang1, Yuxiang Chen1, Shi Zhou3, Huaixin Guo4, Huarui Sun1( )
School of Science and Ministry of Industry and Information Technology Key Laboratory of Micro-Nano Optoelectronic Information System, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
University of Science and Technology of China, Hefei 230026, China
Science and Technology on Monolithic Integrated Circuits and Modules Laboratory, Nanjing Electronic Devices Institute, Nanjing 210016, China
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Graphical Abstract

The authors propose to use the intensity of exciton-induced reflection peaks to quickly and accurately determine the layer numbers in Au-assisted exfoliated large-area MoS2 and WS2 films in a broad thickness range. The method is based on optical interference supported by Fresnel’s theory calculations and is generic to transition metal dichalcogenides (TMDs) supported on different substrates.

Abstract

The emerging Au-assisted exfoliation technique enables the production of a wealth of large-area and high-quality ultrathin two dimensional (2D) crystals. Fast, damage-free, and reliable determination of the layer number of such 2D films can greatly promote layer-dependent physical studies and device applications. Here, an optical method has been developed for simple, high throughput, and accurate determination of the layer number for Au-assisted exfoliated MoS2 and WS2 films in a broad thickness range. The method is based on quantitative analysis of layer-dependent white light reflection spectra (WLRS), revealing that the intensity of exciton-induced reflection peaks can be used as a clear indicator for identifying the layer number. The simple yet robust method will facilitate fundamental studies on layer-dependent optical, electrical, and thermal properties and device applications of 2D materials. The technique can also be readily combined with photoluminescence (PL) and Raman spectroscopies to study other layer-dependent physical properties of 2D materials.

Keywords

Au-assisted exfoliationMoS2 and WS2layer identificationwhite light reflection spectraexcitonic peaks

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Nano Research
Volume 15 Issue 9,
September 2022
Pages 8470-8478
DOI: 10.1007/s12274-022-4418-z
Cite this article:
Zou B, Zhou Y, Zhou Y, et al. Reliable and broad-range layer identification of Au-assisted exfoliated large area MoS2 and WS2 using reflection spectroscopic fingerprints. Nano Research, 2022, 15(9): 8470-8478. https://doi.org/10.1007/s12274-022-4418-z
Topics:
Thickness measurement

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Received: 06 January 2022
Revised: 10 April 2022
Accepted: 11 April 2022
Published: 03 June 2022
© Tsinghua University Press 2022
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