Exfoliation of Transition Metal Dichalcogenides by a High-Power Femtosecond Laser

Sung-Jin An,Mun Seok Jeong,Chanwoo Lee,Yong Hwan Kim,Dae Young Park

doi:10.1038/s41598-018-31374-w

Sung-Jin An, Mun Seok Jeong + Show 3 more

Open Access

https://doi.org/10.1038/s41598-018-31374-w

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Abstract

Thin layer two-dimensional (2-D) transition metal dichalcogenide (TMD) materials have distinctive optoelectronic properties. Therefore, several methods including mechanical exfoliation, chemical vapor deposition, and liquid-phase exfoliation have been attempted to obtain uniform TMDs. However, such methods do not easily produce high-quality few-layer TMDs with high speed. Here, we report the successful fabrication of few-layer TMD materials by femtosecond laser irradiation. It shows that TMD samples can be exfoliated from bulk to ~3 layers. This method is much faster and simpler than other exfoliation methods. The size and number of the layers were confirmed by atomic force microscopy, scanning electron microscopy, Raman spectroscopy, and photoluminescence experiments. It is expected to be used for the mass production of thin 2-D TMD materials.

Highlights

We observed that the transition metal dichalcogenide (TMD) materials were found to be exfoliated with a constant size and number of layers
An amplified Ti:sapphire laser of 80-fs pulse duration with 1-kHz repetition rate and 800-nm center wavelength was focused on the surface of bulk TMD materials
We randomly selected more than 50 nanosheets of various TMD materials (MoS2, WS2, MoSe2, and WSe2) and analyzed them with Atomic force microscopy (AFM) to obtain their average thicknesses

Summary

Introduction

We have studied the exfoliation of the bulk 2-D material to fabricate the thin layers using femtosecond (FS) laser rather than NS laser, because FS laser which has short pulse duration time can minimize the defects caused by heat that can be occurred in laser irradiation process[22,23]. The bulk TMD materials were successfully exfoliated with the several-layered samples. Atomic force microscopy (AFM), scanning electron microscopy (SEM), confocal Raman spectroscopy, and photoluminescence (PL) have been used to identify the size and number of layers of FS laser exfoliated sample.

Results

Conclusion