Stability Of Solid-State Nanopore Fabricated By Dielectric Breakdown

Solid-state nonapores provide the advantages of chemical, thermal mechanical stability, size tunability and integration, which are fast becoming an alternative method to their biological counterparts. Traditional nanopore fabrication methods mainly includes Transmission Electron Microscopy(TEM) and Focused Ion Beam(FIB) techniques. The stability of such nanopores depends on the TEM beam size employed during pore fabrication. Recently, a new fabrication method has been reported to fabricate sub-2nm nanopores by dielectric breakdown, which may provide low cost, high yield and throughput solid-state nanopores. Since this method is totally different from the energetic particle beam based nanopore fabrication, nanopores fabricated by dielectric breakdown may reveal different stability properties. In this paper, we focus on the diameter and conductance stability of the nanopores fabricated by the dielectric breakdown. Nanopores with diameters ranging from 2 nm to 50 nm were studied, all of which were formed in 20-nm silicon nitride (SiNx) membranes directly in 1M PH8 KCl solution. The conductance of the fabricated nanopores was measured under a constant applied voltage (100mV) when immersed in the KCl electrolyte solution. Our experimental results show that nanopores with diameter larger than 4 nm are more stable, and the standard deviation of conductance for these nanopores was 5% within two hours. While for nanopores smaller than 4 nm, the conductance was varied by 10%∼20%.Furthermore, according to our experimental data, nanopores with diameter about 4 nm is proved to be the most stable, exhibiting stable conductance longer than 12 h in 1M KCl PH8 electrolyte solution. Finally, to test the properties of nanopores in DNA sequencing, 20 bases single-stranded DNA (ssDNA), which are Poly (A)20, Poly (C)20,Poly (T)20 and Poly (G)20, were added in cis chamber respectively, showing that nanopore fabricated by dielectric breakdown can discriminate 4 different nucleotides clearly.