Formation of Synthetic Nanopores with Diameters from 20-50 nm by Laser-Assisted Dielectric Breakdown

Abstract

Fabrication of nanopores in synthetic substrated by controlled breakdown (CBD)[1] is a robust and well characterized method that allows sub-2 nm nanopore fabrication, which is a challenge for traditional fabrication methods such as transmission electron microscopy (TEM). Due to its stochastic pore formation process, however, attempts to widen a nanopore using CBD can result in random formation of multiple nanopores instead of increasing the size of a single pore. Since CBD is a broadly-accessible, tuneable, and cost-effective method, it would be useful to fabricate nanopores with diameters from 20 to 50 nm for applications beyond DNA sequencing. This work focuses on fabricating such large nanopores by optically localizing the formation and enlargement of defects in the SiN membrane[2]. We show that the breakdown time of SiN membranes (i.e. time for dielectric breakdown at constant applied potential difference across the membranes) can be lowered significantly by focusing a laser beam on the membrane. To avoid forming multiple nanopores during the enlargement process, low voltage pulses were applied. In this study, differences of parameters between nanopores fabricated by standard CBD and laser-assisted CBD are discussed. The size, number and shape of the resulting nanopores are assessed by various techniques, including protein translocation experiments.[1] Kwok, H.; Briggs, K.; Tabard-Cossa, V. PLoS One 2014, 9, (3), e92880. [2] Pud, S.; Verschueren, D.; Vukovic, N.; Plesa, C.; Jonsson, M. P.; Dekker, C. Nano letters 2015, 15, (10), 7112-7.