Nanoscale electrostatic control in ultra clean van der Waals heterostructures by local anodic oxidation of graphite gates

Abstract

In an all-van der Waals heterostructure, the active layer, gate dielectrics and gate electrodes are assembled from two-dimensional crystals that have a low density of atomic defects. This design allows two-dimensional electron systems with very low disorder to be created, particularly in heterostructures where the active layer also has intrinsically low disorder, such as crystalline graphene layers or metal dichalcogenide heterobilayers. A key missing ingredient has been nanoscale electrostatic control, with existing methods for fabricated local gates typically introducing unwanted contamination. Here we describe a resist-free local anodic oxidation process for patterning sub 100nm features in graphite gates, and their subsequent integration into an all-van der Waals heterostructure. We define a quantum point contact in the fractional quantum Hall regime as a benchmark device and observe signatures of chiral Luttinger liquid behaviour, indicating an absence of extrinsic scattering centres in the vicinity of the point contact. In the integer quantum Hall regime, we demonstrate in situ control of the edge confinement potential, a key requirement for the precision control of chiral edge states. This technique may enable the fabrication of devices capable of single anyon control and coherent edge-state interferometry in the fractional quantum Hall regime.

Main Text: 11 pages, 4 figures | Extended Data: 4 figures | Supplementary Info: 6 pages, 4 figures; updated manuscript post review

References in corpus (11)

• 2D materials and van der Waals heterostructures
• Boron nitride substrates for high-quality graphene electronics
• Micrometer-scale ballistic transport in encapsulated graphene at room temperature
• Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices
• Superconductivity in rhombohedral trilayer graphene
• Spin-Orbit Enhanced Superconductivity in Bernal Bilayer Graphene
• Even denominator fractional quantum Hall state in bilayer graphene
• Fabrication of graphene nanoribbon by local anodic oxidation lithography using atomic force microscope
• Experimental probe of topological orders and edge excitations in the second Landau level
• Half-integer conductance plateau at the $\nu =2/3$ fractional quantum Hall state in a quantum point contact
• Graphene-based quantum Hall interferometer with self-aligned side gates

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• Spontaneous localization at a potential saddle point from edge state reconstruction in a quantum Hall point contact
• Gate-defined Kondo lattices with valley-helical quantum dot arrays
• Residual quantum coherent electron transport in doped graphene leads