Minimizing Residues and Strain in 2D Materials Transferred from PDMS

Abstract

Integrating layered two-dimensional (2D) materials into 3D heterostructures offers opportunities for novel material functionalities and applications in electronics and photonics. In order to build the highest quality heterostructures, it is crucial to preserve the cleanliness and morphology of 2D material surfaces that come in contact with polymers such as PDMS during transfer. Here we report that substantial residues and up to ~0.22% compressive strain can be present in monolayer MoS${}_2$ flakes transferred using PDMS. We show that a UV-ozone pre-cleaning of the PDMS surface before exfoliation significantly reduces organic residues on transferred MoS${}_2$ flakes. An additional 200${}^{\circ }$C vacuum anneal after transfer efficiently removes interfacial bubbles and wrinkles as well as accumulated strain, thereby restoring the surface morphology of transferred flakes to their native state. Our recipe is important for building clean heterostructures of 2D materials and increasing the reproducibility and reliability of devices based on them.

To appear in Nanotechnology (2018)

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Cited by in corpus (25)

• Universal mechanical exfoliation of large-area 2D crystals
• Nonlinear twistoptics at symmetry-broken interfaces
• One-dimensional edge contacts to a monolayer semiconductor
• Ultra-clean assembly of van der Waals heterostructures
• Nanoscale magnetism and magnetic phase transitions in atomically thin CrSBr
• Low-loss integrated nanophotonic circuits with layered semiconductor materials
• Emergence of highly linearly polarized interlayer exciton emission in MoSe${}_2$/WSe${}_2$ heterobilayers with transfer-induced layer corrugation
• Thickness mapping and layer number identification of exfoliated van der Waals materials by Fourier imaging micro-ellipsometry
• Imaging de Haas-van Alphen quantum oscillations and milli-Tesla pseudomagnetic fields
• Macroscopic Single-Phase Monolayer Borophene on Arbitrary Substrates
• Flattening van der Waals heterostructure interfaces by local thermal treatment
• Beam steering with a nonlinear optical phased array antenna
• Second-harmonic generation enhancement in monolayer transition-metal dichalcogenides by an epsilon-near-zero substrate
• Symmetry breaking and spin-orbit coupling for individual vacancy-induced in-gap states in MoS2 monolayers
• Universal transfer and stacking technique of van der Waals heterostructures for spintronics
• Dynamics of an interfacial bubble controls adhesion mechanics in a van der Waals heterostructure
• Nonlocal Exciton-Photon Interactions in Hybrid High-Q Beam Nanocavities with Encapsulated MoS${}_2$ Monolayers
• Impacts of dielectric screening on the luminescence of monolayer WSe${}_2$
• de Haas-van Alphen spectroscopy and fractional quantization of magnetic-breakdown orbits in moiré graphene
• Photonics in Flatland: Challenges and Opportunities for Nanophotonics with 2D Semiconductors
• Dielectric breakdown and sub-wavelength patterning of monolayer hexagonal boron nitride using femtosecond pulses
• Robustness of momentum-indirect interlayer excitons in MoS2/WSe2 heterostructure against charge carrier doping
• Laser-Induced Gas-Phase Transfer and Direct Stamping of Nanomaterials: Comparison of Nanosecond and Femtosecond Pulses
• Magneto-Excitonic Duality From Monolayer to Trilayer CrSBr
• Enhancement of the WS${}_2$ A${}_{1\text{g}}$ Raman Mode in MoS${}_2$/WS${}_2$ Heterostructures