Electromigration current rectification in a cylindrical nanopore due to asymmetric concentration polarization.

We present experimental measurements of electromigration current through a single cylindrical nanopore. A single cylindrical nanopore with 175 nm diameter was fabricated in silicon in series with two micropores with 2 and 100 microm diameters. Thick electrical double layers (EDLs) (kappa a approximately 1) exhibit current rectification due to asymmetric concentration polarization while thinner EDLs show nearly symmetric conductance. After the electric field is turned off, electrical current is measured and observed due to redistribution of ions in the concentration polarization layer.