Ultra-clean assembly of van der Waals heterostructures

Abstract

Layer-by-layer assembly of van der Waals (vdW) heterostructures underpins new discoveries in solid state physics, material science and chemistry. Despite the successes, all current 2D material (2DM) transfer techniques rely on the use of polymers which limit the cleanliness, ultimate electronic performance, and potential for optoelectronic applications of the heterostructures. In this article, we present a novel polymer-free platform for rapid and facile heterostructure assembly which utilises re-usable flexible silicon nitride membranes. We demonstrate that this allows fast and reproducible production of 2D heterostructures using both exfoliated and CVD-grown materials with perfect interfaces free from interlayer contamination and correspondingly excellent electronic behaviour, limited only by the size and intrinsic quality of the crystals used. Furthermore, removing the need for polymeric carriers allows new possibilities for vdW heterostructure fabrication: assembly at high temperatures up to 600°C, and in different environments including ultra-high vacuum (UHV) and when the materials are fully submerged in liquids. We demonstrate UHV heterostructure assembly for the first time, and show the reliable creation of graphene moiré superlattices with more than an order of magnitude improvement in their structural homogeneity. We believe that broad adaptation of our novel inorganic 2D materials assembly strategy will allow realisation of the full potential of vdW heterostructures as a platform for new physics and advanced optoelectronic technologies.

23 pages, 4 figures

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• Electrically-tunable graphene nanomechanical resonators
• Probing Noncentrosymmetric 2D Materials by Fourier Space Second Harmonic Imaging
• Quantum Hall Effect at 0.002T
• Intermediates of Forming Transition Metal Dichalcogenide Heterostructures Revealed by Machine Learning Simulations
• Preserving the Josephson Coupling of Twisted Cuprate Junctions via Tailored Silicon Nitride Circuits Boards
• Atomic imaging of 2D transition metal dihalides
• Substrate pre-sputtering for layer-by-layer van der Waals epitaxy of 2D materials
• Van der Waals devices for surface-sensitive experiments
• Revealing the impact of ambient molecular contamination on scanning tunneling microscopy and spectroscopy of layered materials
• Large-Area Deterministic Stamping of 2D Materials on Arbitrarily Patterned Surfaces