Sensitivity Investigation of Gate Stack Junctionless GaAs FinFET Based NH3 Gas Sensor

This work presents, designing and analysis of gate stack junctionless Gallium Arsenide FinFET (GS-JL GaAs FinFET) for ammonia (NH3) gas sensing application using Cobalt (Co) as sensing gate electrode. To improve the sensing performance and reduce leakage current, stacking of Si02/Hf02 has been used. The sensing mechanism of GS- JL GaAs FinFET NH3 sensor is based on work function modulation of Co upon exposure to NH3. Extensive simulations of proposed sensor have been performed using Sentaurus TCAD simulator. The presence of NH3 is identified by observing the variation in surface potential and other sensing metrics such as threshold voltage, transfer characteristics and transconductance. Sensitivity as a function of OFF current ($S_{I_{OFF}}$), threshold voltage (SVTH) and switching ratio ($S_{I_{ON}/I_{OFF}}$) have also been investigated. Simulation outcomes show that GS-JL GaAs FinFET NH3 sensor offers maximum $S_{I_{OFF}}$ of 4.75 x 10³ SVTH of 0.43 and $S_{I_{ON}/I_{OFF}}$ of 2099 at work function change of 200 meV.