A simple fabrication strategy for orientationally accurate twisted heterostructures

Debnath, R and Sett, S and Biswas, R and Raghunathan, V and Ghosh, A (2021) A simple fabrication strategy for orientationally accurate twisted heterostructures. In: Nanotechnology, 32 (45).

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Abstract

Van der Waals (vdW) heterostructure is a type of metamaterial where multiple layers of 2D materials are vertically aligned at controlled misorientation. The relative rotation in between the adjacent layers, or the twist angle between them plays a crucial role in changing the electronic band structure of the superlattice. The assembly of multi-layers of precisely twisted two dimensional layered materials requires knowledge of the atomic structure at the edge of the flake. It may be artificially created by the 'tear and stack' process. Otherwise, the crystallographic orientation needs to be determined through invasive processes such as transmission electron microscopy or scanning tunneling microscopy, and via second-harmonic generation (SHG). Here, we demonstrate a simple and elegant transfer protocol using only an optical microscope as a edge identifier tool through which, controlled transfer of twisted homobilayer and heterobilayer transition metal dichalcogenides is performed with close to 100 yield. The fabricated twisted vdW heterostructures have been characterized by SHG, Raman spectroscopy and photoluminiscence spectroscopy, confirming the desired twist angle within �0.5° accuracy. The presented method is reliable, quick and prevents the use of invasive tools which is desirable for reproducible device functionalities. © 2021 IOP Publishing Ltd.

Item Type:	Journal Article
Publication:	Nanotechnology
Publisher:	IOP Publishing Ltd
Additional Information:	The copyright for this article belongs to IOP Publishing Ltd
Keywords:	Fabrication; High resolution transmission electron microscopy; Nonlinear optics; Scanning electron microscopy; Scanning tunneling microscopy; Transition metals; Van der Waals forces, Crystallographic orientations; Device functionality; Electronic band structure; Fabrication strategies; Relative rotation; Transfer protocol; Transition metal dichalcogenides; Vertically aligned, Harmonic generation
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering Division of Physical & Mathematical Sciences > Physics
Date Deposited:	02 Dec 2021 11:53
Last Modified:	02 Dec 2021 11:53
URI:	http://eprints.iisc.ac.in/id/eprint/70057

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