Fabrication and Characterization of Back-Gate Controlled Silicon Nanowire based Field-effect pH Sensor

This paper describes the fabrication and characterization of Back-Gate Controlled Silicon Nanowire based Field-effect pH Sensor. Conventional lithography in combination with Inductively Coupled Plasma - Reactive Ion Etching (ICP-RIE) is employed to fabricate Silicon Nanowire. The fabricated device has been characterized under High Power Microscope (HPM), Atomic Force Microscope (AFM), and 3D Profilometer to obtain the surface morphology. For evaluation, the device is tested using three types of pH solutions, pH 4, pH 7, and pH 12. Experimental result of current-voltage (I-V) characteristic is presented according to different pH values. The I-V measurement demonstrated that as the pH value increased, the drain current also increased and vice versa due to the protonation and deprotonation of the oxide surface. High sensitivity of 0.599 nA/pH can be achieved with the width up to 159 nm and 11 nm thickness of the silicon nanowires pH sensor.