Nanopore Fabrication of Two-Dimensional Materials on SiO2 Membranes Using He Ion Microscopy

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Abstract
Structures with pores several nanometers in diameter can be used for distinguishing nucleotides in DNA. A 2D material such as a thin membrane is expected to enhance precise molecule recognition. Here, we present the nanopore fabrication to thin 2D membranes using HIM (He ion microscopy). We transferred three 2D materials of CVD (chemical vapor deposition) graphene, CVD BN, and peel-off MoS$_{2}$, to the sub-micrometer pore of freestanding SiO$_{2}$ membranes on a silicon substrate. The number of atomic layers of the 2D materials was confirmed via Raman spectroscopy and XPS (X-ray Photoelectron Spectroscopy). We examined the reproducibility and accuracy of nanopore fabrication as a function of the focal position and beam irradiation intensity of the HIM system. Reproducible nanopores having diameters of less than 10 nm were realized by optimizing the intensity and focal position. We achieved 1.5-nm-diameter nanopores in a single layer of graphene using this HIM technique.
Funding Information
  • Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research (JP16H03841, JP17K14099)
  • Japan Science and Technology Agency Nanotech Career-up Alliance
  • Murata Science and Education Foundation
  • MEXT Nanotechnology Platform in Osaka University and Kyoto University

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