Clean assembly of van der Waals heterostructures using silicon nitride membranes

Wang, Wendong and Clark, Nicholas and Hamer, Matthew and Carl, Amy and Tovari, Endre and Sullivan-Allsop, Sam and Tillotson, Evan and Gao, Yunze and de Latour, Hugo and Selles, Francisco and Howarth, James and Castanon, Eli G. and Zhou, Mingwei and Bai, Haoyu and Li, Xiao and Weston, Astrid and Watanabe, Kenji and Taniguchi, Takashi and Mattevi, Cecilia and Bointon, Thomas H. and Wiper, Paul V. and Strudwick, Andrew J. and Ponomarenko, Leonid A. and Kretinin, Andrey V. and Haigh, Sarah J. and Summerfield, Alex and Gorbachev, Roman (2023) Clean assembly of van der Waals heterostructures using silicon nitride membranes. Nature Electronics, 6 (12). pp. 981-990. ISSN 2520-1131

Abstract

Van der Waals heterostructures are fabricated by layer-by-layer assembly of individual two-dimensional materials and can be used to create a wide range of electronic devices. However, current assembly techniques typically use polymeric supports, which limit the cleanliness—and thus the electronic performance—of such devices. Here, we report a polymer-free technique for assembling van der Waals heterostructures using flexible silicon nitride membranes. Eliminating the polymeric supports allows the heterostructures to be fabricated in harsher environmental conditions (incompatible with a polymer) such as at temperatures of up to 600 °C, in organic solvents and in ultra-high vacuum. The resulting heterostructures have high-quality interfaces without interlayer contamination and exhibit strong electronic and optoelectronic behaviour. We use the technique to assemble twisted-graphene heterostructures in ultra-high vacuum, resulting in a tenfold improvement in moiré superlattice homogeneity compared to conventional transfer techniques.