Highly Rectifying Conical Nanopores in Amorphous SiO2

Abstract

Nanopore membranes are a versatile platform for a wide range of applications ranging from medical sensing to filtration and clean energy generation. To attain high-flux rectifying ionic flow it is required to produce short channels exhibiting asymmetric surface charge distributions. This work reports on a system of track etched conical nanopores in amorphous SiO 2 membranes, fabricated using the scalable track etch technique. Pores are fabricated by irradiation of 1 µm thick SiO 2 windows with 2.2 GeV 197 Au ions, and subsequent chemical etching. Structural characterisation is carried out using atomic force microscopy, scanning electron microscopy, small angle X-ray scattering, ellipsometry and surface profiling. Conductometric characterisation of the pore surface is performed using a membrane containing 16 pores, including an in depth analysis of ionic transport characteristics. The pores have a tip radius of (5.7 ± 0.1) nm, a