The impact of the distribution of surface charge on the ionic current rectification of nanochannel diodes

Abstract As ionic current rectification (ICR) in nanochannel diodes originates from non-uniformly distributed surface charge, the impact of surface charge on rectification offers many insights. However, previous research mainly focused on the symmetrical bipolar diode and the unipolar diode, and fabricated nanochannel diodes usually deviate from ideal assumptions. Here, we comprehensively discuss the impact of different kinds of surface charge distribution. The results show ICR will become stronger with the increasing algebraic difference of surface charge density, if the surface charge density at one terminal is fixed. When the algebraic difference is the same, ICR in a symmetrical bipolar diode exceeds the maximum. When the surface charge density in two terminals is the same, ICR reaches the maximum if the junction is located in the middle of the nanochannel. Finally, the magnitude of ICR decreases with increasing nanochannel radius. We believe that this work provides a reference for the fabrication of nanochannel diodes.