Electrical Characteristics of Doped Silicon Nanowire Channel Field-Effect Transistor Biosensors

Optimization of operation conditions for biosensing is investigated for the doped silicon nanowire channel transistor sensors. Sensors with phosphorus doped honeycomb nanowire channel are fabricated on 8-in wafer using the conventional CMOS technology. From the low frequency noise characteristics, the noise equivalent gate voltage fluctuation is obtained to evaluate the sensor resolution and optimize the operation condition. The sensor exhibits maximum resolution at the flat band voltage condition. Detection of a neurotransmitter, dopamine, is demonstrated using the fabricated devices, showing a detection limit of 1 fM and a sensitivity of 2.3 mV/log[dopamine] with a resolution of ~60 levels/log[dopamine].