Fabrication of MoS2 Nanopores via Dielectric Breakdown for Single-Molecule Sensing Applications

This study focuses on the controllable fabrication of monolayer molybdenum disulfide (MoS2) nanopores based on dielectric breakdown and their application in single-molecule sensing. To address the poor pore-size controllability and limited reproducibility commonly encountered in the fabrication of sub-5 nm transition metal dichalcogenide (TMD) nanopores, the nanopore formation processes under voltage-stepping and current-stepping modes were systematically investigated. Experimental results demonstrate that, compared with the voltage-stepping mode, the current-stepping mode exhibits a more gradual breakdown transition. Although the average breakdown times of the two modes are comparable, the nanopores fabricated by current stepping are confined to a narrower sub-5 nm range, whereas voltage stepping produces a broader distribution. Consequently, precise and controllable fabrication of sub-5 nm TMD nanopores was achieved. The fabricated MoS2 nanopore sensor was further employed for single-molecule detection of oligonucleotide (Oligo) DNA, where distinct ionic current blockade events were successfully recorded. Combined with COMSOL Multiphysics simulations, three representative translocation behaviors were identified and elucidated. This work provides systematic experimental and theoretical insights into the high-precision fabrication of TMD nanopores and their potential applications in biosensing.