  Ionic Current Rectification (ICR) can appear in nanopores, causing a
diode-like behavior that originates from different efficiency of ion transport
through the pore channel with respect to the applied voltage bias polarity.
This effect is particularly interesting for nanopores with a short channel
length, that is smaller than 500 nm, because then the dependence of the ion
current on the direction along which the ions pass through the channel is
determined by the geometry and material of the nanopore, and by the ion
concentration in the electrolyte. Surface charges can play an important role,
and therefore nanopores consisting of multiple materials can induce ICR because
of different charge distributions at the nanopore-electrolyte interface for the
different material sections. In this work, we study four solid-state nanopore
designs considering different geometries of charge distributions along the
inner and outer surfaces of nanopores, and evaluate their impact on ICR with
six different electrolytes. The direct comparison between experimental data and
modeling enables to understand how the different surface charge configurations
impact the ICR.
