New Approach Advances Residue-Free 2D Material Transfer

In a study recently published in the Journal of Nanotechnology, a new technique was proposed to prevent residue and contamination of 2D materials during their transfer.

Study: Graphene in suspension without residue transferred by perforated template. Image Credit: megaflopp/Shutterstock.com

What is Graphene?

Graphene and some other two-dimensional (2D) components have unusual properties and still arouse curiosity in many scientific fields due to their potential uses in optoelectronics, high-temperature superconductors, wearable electronics, fuel cells, genetic analysis, as well as other fields. .

Nevertheless, to effectively use two-dimensional tools, the transmission of reference material to the surface of a component is necessary for both material fabrication and property categorization.

Nearly all of the currently accessible methodologies for component transmission use carrier polymer materials that envelope or extensively interact with the conductive polymers.

Schematic of the transfer method for fabricating graphene in suspension using perforated jigs.  (a) Preparation of the perforated polymer model (PT).  (b) Transfer of graphene onto the PT.  (c) Transfer of graphene onto the perforated SiO2/Si substrate.  (scale bar is 20 µm).

Figure 1. Schematic of the transfer method for fabricating graphene in suspension using perforated jigs. (a) Preparation of the perforated polymer model (PT). (b) Transfer of graphene onto the PT. (c) Graphene transfer on perforated SiO2/Substrate Si. (scale bar is 20 μm). © Kim, SM et al. (2022).

Different Transfer Methods

Transmission polyesters are commonly used for wet motion and are generally assigned to the skin of two-dimensional materials via spin coating.

Following the phase transition, these transmission plastics are dispersed using either particular etchants such as acetonitrile or by thermal degradation at high heat in the oxidant range.

Nevertheless, it is well known that even after continuous etching in different solvents preceded by enhanced growth heat treatment, it is extremely difficult to truly remove these polymeric supports from the exterior of two-dimensional materials, resulting in polymeric contaminants. important outside of two-dimensional materials.

These contaminants can negatively influence the functioning of the conjugated polymers.

Transfer methods for CVD-graphene

Additional transfer methods for huge CVD-graphene without thermoplastics have already been suggested for huge CVD-graphene. This can be achieved by explicitly etching the fundamental Cu sheets, by humidity technique, using an organic solvent rather than a polymer support, or by clearly peeling off the graphene with H2 bubbles and so on.

However, using these methodologies to fabricate residue-free locked two-dimensional materials on a porous medium is challenging because the dissolved two-dimensional components are damaged by the surface tension applied by the fluids used in wet transmission.

Nevertheless, using wet transmission methodologies, a few ways to fabricate suspension graphene without polyethylene impurities have been recommended.

The majority of these techniques consist of placing a sheet of CVD-graphene/copper directly on the grid of transmission electron microscopes without the need for a polymer support. Graphene dissolved on the grid of transmission electron microscopes is acquired by etching copper foil.

Images and illustrations of the separation of graphene/PT from the SiO2/Si substrate.  (a) successful case and (b) unsuccessful case.  (scale bar is 50 µm).

Figure 2. Images and illustrations of the separation of graphene/PT from SiO2/Substrate If. (a) successful case and (b) unsuccessful case. (scale bar is 50 μm). © Kim, SM et al. (2022).

Limits of previous techniques

Even though these techniques can reduce the potency of polymeric contaminants, the region of dissolved graphene is extremely small and is limited to high transmission electron microscope measurements.

Such techniques, in general and in particular, usually use huge CVD graphene, and dissolved graphene is randomly or stochastically acquired by a material with many openings, which makes it difficult to algorithmically transfer small-area graphene, at the target location in a broken material. .

Proposed methodology

Besides interaction with the substrate, contaminants in polyethylene can affect the productivity as well as the properties of two-dimensional materials. Therefore, no polymers should be placed in used or controlled areas to avoid negative influences.

To avoid the accumulation of polymers in the target gene, a new transfer technique has been established to transfer graphene as well as other two-dimensional substances onto target surfaces free of polymeric contaminants in particular and pre-selected territories.

Graphene can be directly moved and suspended over multiple lengths of openings, ditches, and holes using pre-engineered ruptured polymer layouts, eliminating the need for spin-coating or encompassing large graphene with a thermoplastic.

Even though the proposed technique can also be classified as a desiccated support system, it allowed to fabricate huge dissolved graphenes without polymer impurities, whether the graphene is CVD or immaculate.

The new framework is believed to improve two-dimensional materials and coatings research communities by making it easier to explore the unique characteristics of two-dimensional materials without having to think about the effects of synthetic polymeric contaminants and nutrient engagement.

Results of TEM analysis.  (a) TEM image of graphene (TEM grid is inset).  (b) High magnification TEM image (the fast Fourier transform (FFT) pattern is the inset).  (c) Conventional PMMA-based transfer technique where polymer residues completely cover the graphene surface (FFT pattern is inset).

Picture 3. Results of TEM analysis. (a) TEM image of graphene (TEM grid is inset). (b) High magnification TEM image (the fast Fourier transform (FFT) pattern is the inset). (c) Conventional PMMA-based transfer technique where polymer residues completely cover the graphene surface (FFT pattern is inset). © Kim, SM et al. (2022).

Conclusion and perspectives of the research

In conclusion, a novel graphene transmission technique has been suggested that can precisely and explicitly transmit graphene onto the target substrate without synthetic polymeric contaminants and create false suspension frames over openings, ditches and gaps.

It was conclusively concluded that pristine graphene could be directly transmitted on the fractured SiO2/ Si substrate without polymer expulsion or thermal degradation using a prefabricated polymer structure with a preconfigured sequence.

Light microscopy was used to examine PT/graphene filtration from SiO2Substrate /Si deeper.

Reference

Kim, SM et al. (2022). Graphene in suspension without residue transferred by perforated template. Nanotechnology. Available at: https://iopscience.iop.org/article/10.1088/1361-6528/ac4664

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