Thickness-dependent dielectric breakdown and nanopore creation on sub-10-nm-thick SiN membranes in solution

Abstract

Recently, dielectric breakdown of solid-state membranes in solution has come to be known as a powerful method for fabricating nanopore sensors. This method has enabled a stable fabrication of nanopores down to sub-2 nm in diameter, which can be used to detect the sizes and structures of small molecules. Until now, the behavior of dielectric breakdown for nanopore creation in SiN membranes with thicknesses of less than 10 nm has not been studied, while the thinner nanopore membranes are preferable for nanopore sensors in terms of spatial resolution. In the present study, the thickness dependence of the dielectric breakdown of sub-10-nm-thick SiN membranes in solution was investigated using gradually increased voltage pulses. The increment in leakage current through the membrane at the breakdown was found to become smaller with a decrease in the thickness of the membrane, which resulted in the creation of smaller nanopores. In addition, the electric field for dielectric breakdown drastically decreased when the thickness of the membrane was less than 5 nm. These breakdown behaviors are quite similar to those observed in gate insulators of metal-oxide-semiconductor devices. Finally, stable ionic-current blockades were observed when single-stranded DNA passed through the nanopores created on the membranes with thicknesses of 3–7 nm.

Optically-Monitored Nanopore Fabrication Using a Focused Laser Beam

“…S3 , Table S1 ). Given that our nanopore fabrication strategy is markedly different than existing techniques such as CBD or TEM-drilling, we cannot expect that the standard conductance model 34 , 35 for pore size determination applies; in particular, this model assumes an effective nanopore height equivalent to or one third of the membrane thickness, depending on the method employed 27 , 36 , 37 . Instead, we can reliably estimate the nanopore diameter according to the translocation blockage level using a molecular ruler of known dimensions, such as dsDNA (2.2 ± 0.1 nm), and the following equations 38 : where and are the open and blocked pore current levels, respectively, l is the local membrane thickness, d the pore diameter, the solution conductivity and a is the analyte diameter.…”

Biomimetic potassium-selective nanopores

“…In the dielectric breakdown process, both chambers of a custom-made polydimethylsiloxane conductivity cell were filled with a strongly acidic solution of 1 M KCl (pH 1.6) ( 32 , 33 ). The dielectric breakdown was performed with 12 V applied with two Ag/AgCl pellet electrodes.…”

Application of Solid-State Nanopore in Protein Detection

“…Thinning the membrane is important for high vertical resolution, but an ultrathin membrane has the risk of fracture. Yanagi et al developed a new fabrication process that employs a polycrystalline-Si (poly-Si) sacrificial layer providing mechanical robustness to the membrane [126]; the effective thickness of the nanopores was estimated to range from 0.6 to 2.2 nm with diameter smaller than 2 nm [127]. A SiN nanopore with a 0.5-nm diameter at the waist was sputtered using a tightly focused, high-energy electron beam in a scanning transmission electron microscope (STEM) [107,108,128].…”