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 (NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>) 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 NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> sensor is based on work function modulation of Co upon exposure to NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>. Extensive simulations of proposed sensor have been performed using Sentaurus TCAD simulator. The presence of NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> 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 (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S_{I_{OFF}}$</tex>), threshold voltage (SV<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</inf>) and switching ratio (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S_{I_{ON}/I_{OFF}}$</tex>) have also been investigated. Simulation outcomes show that GS-JL GaAs FinFET NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> sensor offers maximum <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S_{I_{OFF}}$</tex> of 4.75 x 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> SV<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</inf> of 0.43 and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S_{I_{ON}/I_{OFF}}$</tex> of 2099 at work function change of 200 meV.