Comparison between Scotch tape and gel‐assisted mechanical exfoliation techniques for preparation of 2D transition metal dichalcogenide flakes

Abstract

The traditional use of Scotch tape for exfoliating layers of two-dimensional (2D) transition metal dichalcogenides (TMDs) has been compared with a gel-assisted mechanical exfoliation technique, using MoS 2 as a representative TMD. The gel-assisted exfoliation process, which makes use of both Scotch tape and a gel film, is superior to the use of Scotch tape alone, as it gives a higher probability of obtaining larger surface area few-layer flakes. A quantitative analysis has been made between the samples prepared by the two techniques. The total density of flakes transferred onto a sample by Scotch tape alone was much higher than when using the gel film. However, most of the transferred flakes were several microns in thickness with lateral dimensions <10 µm. Therefore, the higher percentage of few-layer flakes with large lateral dimensions (> 20 µm) transferred using gel film is very advantageous. Since samples prepared using gel film have fewer flakes, the contacting of potential thin flakes on the sample can be done conveniently. Also, unlike Scotch tape, the gel film does not leave adhesive residue on the substrate. Optical microscopy, contrast difference measurements and Raman spectroscopy were used for identification of the few-layer MoS 2 flakes.

Edge‐Orientation Dependent Nanoimaging of Mid‐Infrared Waveguide Modes in High‐Index PtSe2

“…The PtSe 2 planar waveguides studied here were fabricated by gel‐assisted mechanical exfoliation [ 19 ] of a bulk PtSe 2 crystal onto standard SiO 2 /Si wafers (see Experimental Sectionfor the sample fabrication). Figure a shows the crystal structure of the PtSe 2 along the [210] and [001] directions.…”

“…The substrates used for fabricating the PtSe 2 planar waveguides were silicon wafers with 300 nmthick thermal oxide layers on top. PtSe 2 flakes were then transferred onto the substrates by gel‐assisted mechanical exfoliation [ 19 ] from a high‐quality (99.9999% purity) PtSe 2 crystal (https://www.2dsemiconductors.com).…”

The Magnetic Genome of Two-Dimensional van der Waals Materials

“…This method involves physically cleaving layers from single crystals with adhesive polymers (such as commercially available tape or polydimethylsiloxane (PDMS)). 548 , 550 − 552 The process flow is simple: place a single crystal on the adhesive polymer, fold and unfold the adhesive polymer several times, then transfer the polymer with exfoliated flakes onto the desired substrate (often quartz, sapphire, or SiO 2 ). 553 − 555 This process can be done within an inert environment (such as a glovebox) without exposing flakes to solvents, heat, or atmosphere, which is ideal for air- and moisture-sensitive vdW magnets.…”

A Review of the Synthesis, Properties, and Applications of 2D Materials

“…Figure 3 illustrates a schematic diagram of a laser exfoliation process for the synthesis of nanosheets of MoS 2 , WS 2 , MoSe 2 , and WSe 2 from bulk TMD materials. A com parison study of the characteristics of TMDMoS 2 produced by scotch tape and gelassisted mechanical exfoliation method was done by Budania et al [38] The gelassisted exfoliation pro duced MoS 2 and left no residue on the substrate materials. In addition, the transferred flakes had a lower density than the TMDMoS 2 produced by scotch tape.…”

“…A comparison study of the characteristics of TMD‐MoS 2 produced by scotch tape and gel‐assisted mechanical exfoliation method was done by Budania et al. [ 38 ] The gel‐assisted exfoliation produced MoS 2 and left no residue on the substrate materials. In addition, the transferred flakes had a lower density than the TMD‐MoS 2 produced by scotch tape.…”