Improved Gain and Bandwidth of Water-Gated Field Effect Transistor (WG-FET) Circuits Using Solutions with Higher Ion Concentration

This paper presents, for the first time, the improvement of gain and bandwidth of water-gated field effect transistor (WG-FET) circuits using higher ion concentrations of NaCl solutions. WG-FET is fabricated using 16-nm-thick single crystalline silicon film and inert gold electrodes. The gain and bandwidth of a common source amplifier built using WG-FET depend mostly on the resistance of solution droplet and electrical double layer (EDL) capacitances. Increasing the molarity from DI-water to 20 mM increases the gain of the common source amplifier at 5 Hz from 1.65 dB to 8.05 dB and the unity-gain frequency from 10 Hz to 1 kHz.