Scaled-up Synthesis of Freestanding Molybdenum Disulfide Membranes for Nanopore Sensing.

Two-dimensional (2D) materials, owing to their extremely low thickness, are ideal materials for nanopores with optimal detection sensitivity and resolution. Among 2D materials, molybdenum disulfide (MoS 2 ) has gained significant traction as a more suitable nanopore material compared to graphene, which is much more hydrophobic. However, performing experiments using 2D nanopores remains challenging due to the lack of scalable fabrication methods of high-quality freestanding membranes. Here we report a site-directed, scaled-up synthesis of MoS 2 freestanding membranes on predrilled nanoapertures on 4-inch wafer substrates with 75% yields. A unique chemical vapor deposition (CVD) method that introduces sulfur and molybdenum dioxide vapors across both sides of the sub-100 nm nanoapertures results in the exclusive formation of freestanding membranes that seal the apertures. Nucleation and growth near the nanoaperture edges is followed by nanoaperture decoration with MoS 2 which proceeds until a critical flake radius of curvature is achieved, after which fully spanning freestanding membranes form. Intentionally blocking flow of reagents through the apertures inhibits MoS 2 nucleation around the nanoapertures, thereby promoting the formation of large-crystal monolayer MoS 2 membranes. The in situ grown membranes along with facile membrane wetting and nanopore formation using dielectric breakdown enabled the recording of dsDNA translocation events at 1 MHz bandwidth, unprecedented for 2D nanopores. The methods presented here are important steps towards the development of many applications requiring single-layer membranes built at-scale in high-throughput 2D nanofluidics and nanopores studies. This article is protected by copyright. All rights reserved.