Investigation of field effects in a solid-state nanopore transistor.

In order to calculate ion currents through solid-state nanopore transistors realistically, we propose a computational model based on the Poisson-Nernst-Plank equation. In the present model, we determine the surface charge density locally on the nanopore by imposing consistency between the ion distribution and the chemical reaction at the surface. The model can consider a non-uniform influence by the gate voltage on the inner surface of the nanopore membrane, which enables us to investigate ion currents depending on the gate geometry such as the thickness and vertical position within the nanopore. We verify the validity of the model by comparing the pH dependence of simulation results with the extant experimental results. We also investigate the transistor behaviour depending on the surface material, pore geometry and gate position. In particular, we propose an optimized system to enhance the on/off ratio of the nanopore transistor.