Investigation of the Salt Concentration Dependence of Water-Gated Field Effect Transistors (WG-FET) Using 16-nm-Thick Single Crystalline Si Film

Abstract

This paper presents the effect of NaCl concentration on the operation of a water-gated field effect transistor (WG-FET) that uses 16-nm-thick single crystalline silicon (Si) film. In WG-FET, electrical double layer (EDL) formed at the water/silicon interface behaves as gate dielectric and this fluidic interface makes WG-FET a suitable device for sensing applications. Characteristics of EDL and the threshold voltage of WG-FET depend on the molarity of solution. Increasing the molarity of NaCl solution from 0.5 to 65 mM changes the threshold voltage from 360 to 465 mV. Accordingly, drain current of the WG-FET device changes with NaCl concentration.

Keywords

• water-gated transistor
• microfluidic interface
• electrical double layer
• salt sensor