Minimizing residues and strain in 2D materials transferred from PDMS

Jain, Achint; Bharadwaj, Palash; Heeg, Sebastian; Parzefall, Markus; Taniguchi, Takashi; Watanabe, Kenji; Novotny, Lukas

doi:10.1088/1361-6528/aabd90

Cited by 138 publications

(145 citation statements)

References 54 publications

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“…The glue residues mainly depend on different tapes, for the white tape (3 M scotch) or blue tape (Nitto), there will be some glue left on substrate, which can be removed by further annealing if required by the subsequent measurement. However, we can also use home-made polydimethylsiloxane (PDMS) to replace these tapes as transfer media, which can make the substrate much cleaner 54 . The thickness of Au/Ti layer is a crucial factor.…”

Section: Methodsmentioning

confidence: 99%

Universal mechanical exfoliation of large-area 2D crystals

et al. 2020

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Two-dimensional materials provide extraordinary opportunities for exploring phenomena arising in atomically thin crystals. Beginning with the first isolation of graphene, mechanical exfoliation has been a key to provide high-quality two-dimensional materials, but despite improvements it is still limited in yield, lateral size and contamination. Here we introduce a contamination-free, one-step and universal Au-assisted mechanical exfoliation method and demonstrate its effectiveness by isolating 40 types of single-crystalline monolayers, including elemental two-dimensional crystals, metal-dichalcogenides, magnets and superconductors. Most of them are of millimeter-size and high-quality, as shown by transfer-free measurements of electron microscopy, photo spectroscopies and electrical transport. Large suspended two-dimensional crystals and heterojunctions were also prepared with high-yield. Enhanced adhesion between the crystals and the substrates enables such efficient exfoliation, for which we identify a gold-assisted exfoliation method that underpins a universal route for producing large-area monolayers and thus supports studies of fundamental properties and potential application of two-dimensional materials.

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Section: Methodsmentioning

confidence: 99%

Universal mechanical exfoliation of large-area 2D crystals

et al. 2020

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“…These two peak positions are slightly smaller than those from strain‐free 2D Te flakes with similar thickness. [ 77–80 ] Such a slight shift for the A 1 ‐mode and E 2 ‐mode peaks is likely due to the existence of residual stress introduced from the transfer [ 81 ] and LB assembly [ 82–84 ] processes. In our experiment, we maintain the same parameters for all transfer and LB assembly steps.…”

Section: Figurementioning

confidence: 99%

Strain‐Engineered Anisotropic Optical and Electrical Properties in 2D Chiral‐Chain Tellurium

et al. 2020

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Atomically thin materials, leveraging their low‐dimensional geometries and superior mechanical properties, are amenable to exquisite strain manipulation with a broad tunability inaccessible to bulk or thin‐film materials. Such capability offers unexplored possibilities for probing intriguing physics and materials science in the 2D limit as well as enabling unprecedented device applications. Here, the strain‐engineered anisotropic optical and electrical properties in solution‐grown, sub‐millimeter‐size 2D Te are systematically investigated through designing and introducing a controlled buckled geometry in its intriguing chiral‐chain lattice. The observed Raman spectra reveal anisotropic lattice vibrations under the corresponding straining conditions. The feasibility of using buckled 2D Te for ultrastretchable strain sensors with a high gauge factor (≈380) is further explored. 2D Te is an emerging material boasting attractive characteristics for electronics, sensors, quantum devices, and optoelectronics. The results suggest the potential of 2D Te as a promising candidate for designing and implementing flexible and stretchable devices with strain‐engineered functionalities.

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“…1a). The stamping process mediated by PDMS lm is simple to perform and was widely adapted in many prior studies (Dean et al 2010;Jain et al 2018;Rosenberger et al 2018). In particular, the PDMS-based stamping process has been primarily used to fabricate 2D vertical heterostructures (Dean et al 2010).…”

Section: Resultsmentioning

confidence: 99%

“…Previous TEM investigations revealed that 2D crystals prepared using various sample preparation processes suffer from surface contamination In this study, we explored the potential of using atomic force microscopy (AFM) to remove surface residues from 2D crystals (Goossens et al 2012;Jain et al 2018;Lindvall et al 2012;Rosenberger et al 2018; Schweizer et al 2020). Using various TEM investigations, we con rmed that polydimethylsiloxane (PDMS) residues on graphene samples are effectively removed by contact-mode AFM sweeping.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Removal of Surface Residues on Graphene for TEM Characterizations

KIM

Lee

Kim

2020

Preprint

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Contamination on two-dimensional (2D) crystal surfaces poses serious limitations on fundamental studies and applications of 2D crystals. Surface residues induce uncontrolled doping and charge carrier scattering in 2D crystals, and trapped residues in mechanically assembled 2D vertical heterostructures often hinder coupling between stacked layers. Developing a process that can reduce the surface residues on 2D crystals is important. In this study, we explored the use of atomic force microscopy (AFM) to remove surface residues from 2D crystals. Using various transmission electron microscopy (TEM) investigations, we confirmed that surface residues on graphene samples can be effectively removed via contact-mode AFM scanning. The mechanical cleaning process dramatically increases the residue-free areas, where high-resolution imaging of graphene layers can be obtained. We believe that our mechanical cleaning process can be utilized to prepare high-quality 2D crystal samples with minimum surface residues.

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Minimizing residues and strain in 2D materials transferred from PDMS

Cited by 138 publications

References 54 publications

Universal mechanical exfoliation of large-area 2D crystals

Universal mechanical exfoliation of large-area 2D crystals

Strain‐Engineered Anisotropic Optical and Electrical Properties in 2D Chiral‐Chain Tellurium

Mechanical Removal of Surface Residues on Graphene for TEM Characterizations

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