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

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.

Unveiling defect-mediated carrier dynamics in monolayer semiconductors by spatiotemporal microwave imaging

“…3A. The much narrower PL spectrum (Supplementary Information S5) of Sample B than Sample A indicates that the former is cleaner (33), consistent with the general view that exfoliated TMD monolayers are usually less defective than the CVD grown monolayers (34,35). Surprisingly, during our measurement on over 10 TMD samples, we have systematically observed that the photoconductivity in exfoliated monolayers is always lower than that in CVD ones.…”

MoS2 Nanosheets with Narrowest Excitonic Line Widths Grown by Flow-Less Direct Heating of Bulk Powders: Implications for Sensing and Detection

“…Hence, even though the ME technique for obtaining high-quality 2D samples is attractive, its poor yield, 128 uncontrollable and irregular sample homogeneity, and not being scalable makes this technique unsuitable for almost any practical applications. 128,129 Chemical vapor deposition (CVD), on the other hand, is a scalable technique, where, unlike ME, large-scale single crystals of 2D-TMDs with uniform layer-thicknesses over lateral sizes reaching hundreds of micrometers can be produced. 52,130 In CVD, TMDs are typically grown using MoO 3 and X (X=S, Se, W etc.)…”

Enhanced Thermal Conductivity of Silicone Composites Filled with Few-Layered Hexagonal Boron Nitride

“…Thus, we can obtain a large aspect ratio if we decrease the thickness of filler. According to the existing research, the preparation of two-dimensional nanomaterials generally includes a micro-mechanical exfoliation method [ 22 ], ball milling [ 23 , 24 ], laser exfoliation [ 25 ], liquid exfoliation [ 26 , 27 , 28 ], a lithium intercalation method [ 29 ] and chemical vapor deposition (CVD) [ 30 , 31 ]. Fan et al demonstrated a novel approach to fabricate boron nitride nanosheets (BNNS) via hypochlorite-assisted ball milling.…”