Scanning Tunneling Microscopy of an Air Sensitive Dichalcogenide Through an Encapsulating Layer

Abstract

Many atomically thin exfoliated 2D materials degrade when exposed to ambient conditions. They can be protected and investigated by means of transport and optical measurements if they are encapsulated between chemically inert single layers in the controlled atmosphere of a glove box. Here, we demonstrate that the same encapsulation procedure is also compatible with scanning tunneling microscopy (STM) and spectroscopy (STS). To this end, we report a systematic STM/STS investigation of a model system consisting of an exfoliated 2H-NbSe2 crystal capped with a protective 2H-MoS2 monolayer. We observe different electronic coupling between MoS2 and NbSe2, from a strong coupling when their lattices are aligned within a few degrees to 2 essentially no coupling for 30° misaligned layers. We show that STM always probes intrinsic NbSe2 properties such as the superconducting gap and charge density wave at low temperature when setting the tunneling bias inside the MoS2 band gap, irrespective of the relative angle between the NbSe2 and MoS2 lattices. This study demonstrates that encapsulation is fully compatible with STM/STS investigations of 2D materials.

arXiv comment19 pages, 5 figures

References in corpus (22)

• Electric Field Effect in Atomically Thin Carbon Films
• Two-Dimensional Gas of Massless Dirac Fermions in Graphene
• Atomically thin MoS2: A new direct-gap semiconductor
• Two Dimensional Atomic Crystals
• Magic-angle graphene superlattices: a new platform for unconventional superconductivity
• Layer-dependent Ferromagnetism in a van der Waals Crystal down to the Monolayer Limit
• Discovery of intrinsic ferromagnetism in 2D van der Waals crystals
• The Valley Hall Effect in MoS2 Transistors
• Gate-induced insulating state in bilayer graphene devices
• Emergence of Superlattice Dirac Points in Graphene on Hexagonal Boron Nitride
• Commensurate-incommensurate transition for graphene on hexagonal boron nitride
• Edge conduction in monolayer WTe2
• Superconductivity protected by spin-valley locking in ion-gated MoS2
• Quality heterostructures from two dimensional crystals unstable in air by their assembly in inert atmosphere
• Direct imaging of the band profile in single layer $Mo{S}_2$ on graphite: quasiparticle energy gap, metallic edge states and edge band bending
• Strong interface-induced spin-orbit coupling in graphene on WS2
• Fast pick up technique for high quality heterostructures of bilayer graphene and hexagonal boron nitride
• Gate-induced Superconductivity in atomically thin MoS2 crystals
• Momentum-space indirect interlayer excitons in transition metal dichalcogenide van der Waals heterostructures
• A quantum phase transition from triangular to stripe charge order in NbSe${}_2$
• Mechanical cleaning of graphene
• Microscopic Origin of the Valley Hall Effect in Transition Metal Dichalcogenides Revealed by Wavelength Dependent Mapping

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• The composition and structure of the ubiquitous hydrocarbon contamination on van der Waals materials
• A non-invasive dry-transfer method for fabricating mesoscopic devices on sensitive materials
• Delusive chirality and periodic strain pattern in moiré systems
• Multiband charge density wave exposed in a transition metal dichalcogenide