ELECTROCHEMICAL FIELD-EFFECT AS A PROBE OF DOUBLE-LAYER DYNAMICS

We describe a silicon field-effect structure where the gate consists of an electrolyte instead of the classical metal gate and insulator layer. The active part of the structure is an n-inversion layer on p-Si as in ordinary metal-oxide-semiconductor field-effect transistors. We demonstrate its operation and discuss its characteristics on the basis of n-Si/polymer-electrolyte interfaces with high-density accumulation layers similar to an inversion layer. Upon decreasing the operating temperature, the transient behavior of the charge accumulation starts exhibiting memory effects with a logarithmic time dependence in the 1 s to 1 day range, attributed to the kinetics of ion accumulation in the polymer. In this time range, the electrochemical field effect offers a better way to investigate interface charge dynamics than usual methods. Relaxation models are presented and related to the glassy transition of the polymer electrolyte, suggesting that specificities of the interface do affect the ion kinetics in the polymer.