SiNW-CMOS Hybrid Common-Source Amplifier as a Voltage-Readout Hydrogen Ion Sensor

Abstract

We proposed a silicon nanowire (SiNW)-CMOS hybrid common-source amplifier (CSA) as a voltage-readout hydrogen ion sensor and fabricated it on a 6-in silicon-on-insulator wafer using a conventional back-end process and a wafer-level top-down process. The current-defined sensitivity Δ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IDS</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IDS</i> of the SiNW itself was 0.18, and the maximum output voltage shift found in the CSA configuration was 38.1 mV/pH. A simple analytical model showed that the voltage-defined sensitivity can be controlled and maximized by the gate voltage of the MOSFET, indicating that process variations of SiNWs are electrically controllable in a SiNW-based sensor array system with the voltage-readout scheme.