Gentle transfer method for water- and acid/alkali-sensitive 2D materials for (S)TEM study

Abstract

We report a method in making transmission electron microscopy sample for both CVD-grown and exfoliated 2D materials without etching process, thus gentle to those 2D materials that are sensitive to water and reactive etchants. Large-scale WS2 monolayer grown on glass, NbS2 atomic layers grown on exfoliated h-BN flakes, and water-sensitive exfoliated TiS2 flakes are given as representative examples. We show that the as-transferred samples not only retain excellent structural integrity down to atomic scale but also have little oxidations, presumably due to the minimum contact with water/etchants. This method paves the way for atomic scale structural and chemical investigations in sensitive 2D materials.

Tuning Electrical Conductance in Bilayer MoS2 through Defect-Mediated Interlayer Chemical Bonding

“…The isopropyl alcohol droplet assisted method was used to transfer 2D flakes to the TEM grid. 61 STEM imaging and EELS analysis were performed on a FEI Titan Themis G2 doubleaberration-corrected TEM with a super energy dispersive X-ray (EDX) spectroscopy detector operating at 60 kV. A low-voltage modified Gatan GIF Quantum spectrometer was used for recording the EELS spectra.…”

Defects and Surface Structural Stability of MoTe2 Under Vacuum Annealing

“…A MoTe 2 thin flake is transferred onto a Protochips in situ heating grid by poly(bisphenol A carbonate) assisted wet transfer method. 50 In order to avoid electron beam-induced damage, STEM imaging is performed on an aberrationcorrected JEM-ARM200F (JEOL USA Inc.) operating at 80 kV. The convergence semiangle of the electron beam is 25 mrad, while the collection semiangle for the annular dark field (ADF) detector is 70− 370 mrad.…”

High-Fidelity Transfer of Chemical Vapor Deposition Grown 2D Transition Metal Dichalcogenides via Substrate Decoupling and Polymer/Small Molecule Composite

“…Dry transfer does not work well due to the stronger bonding between the TMD and the substrate (see Figures S1 and S2, Supporting Information). On the other hand, wet transfer methods may rely on harsh chemical processing and often leave organic residue, wrinkles, and cracks, which could degrade the properties of the materials. , For example, a significant impact on the electronic transport properties for the graphene and TMD devices using such transfer has been reported. − Moreover, organic residues can also influence the optical properties and lead to contaminations in electron microscopic imaging. − A gentle transfer method that neither leaves residue nor degrades the properties of CVD grown monolayer TMDs is thus critically needed for both studying their fundamental physical properties and for device applications.…”