Stability analysis and optimization of stack oxide junctionless finFET based ammonia gas sensor

This work explores, designing and analysis of stack oxide junctionless FinFET (SO-JL FinFET) based ammonia (NH3) gas sensor. In order to detect the presence of NH3, Cobalt (Co) is used as catalytic gate electrode with stacking of SiO2/HfO2 as oxide. The proposed device has been designed using Sentaurus TCAD simulator and to validate the simulation methods and models, the junctionless FinFET has been calibrated with the experimental results. The sensing performance of SO-JL FinFET NH3 sensor is illustrated through change in work function of gate upon exposure to ammonia which alters various sensing metrices of the sensor. Variation in surface potential and other electrical parameters such as threshold voltage (VTH), transfer characteristics, switching ratio (ION/IOFF), OFF current, threshold voltage, switching ratio and subthreshold slope sensitivity (SIOFF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${S}_{{I}_{OFF}}$$\end{document}, SVTH\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${S}_{{V}_{TH}}$$\end{document}, SIONIONIOFFIOFF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S_{{{\raise0.7ex\hbox{${I_{ON} }$} \!\mathord{\left/ {\vphantom {{I_{ON} } {I_{OFF} }}}\right.\kern-0pt} \!\lower0.7ex\hbox{${I_{OFF} }$}}}}$$\end{document} and SSS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${S}_{SS}$$\end{document} respectively) have been analyzed at different concentration of ammonia gas. Simulation results reveal that proposed sensor exhibit high SIOFF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${S}_{{I}_{OFF}}$$\end{document} of 5.65 x 103, SVTH\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${S}_{{V}_{TH}}$$\end{document} of 0.51 and SIONIONIOFFIOFF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S_{{{\raise0.7ex\hbox{${I_{ON} }$} \!\mathord{\left/ {\vphantom {{I_{ON} } {I_{OFF} }}}\right.\kern-0pt} \!\lower0.7ex\hbox{${I_{OFF} }$}}}}$$\end{document} of 3.851 x 103 at work function change (Delta phi M\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta {\phi }_{M}$$\end{document}) of 250 meV. Fin width and Fin height have been optimized to ensure high sensitivity. Additionally, to test the repeatability and stability of proposed device, statistical analysis has been carried out to evaluate coefficient of variation of sensitivity parameters. The proposed sensor has also been examined for reproducibility and results obtained demonstrate that SO-JL FinFET NH3 sensor is repeatable and adequately stable with settling time of 1.42 ns at Delta phi M\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta {\phi }_{M}$$\end{document} = 250 meV. Further, the reliability of SO-JL FinFET NH3 gas sensor has been investigated over wide temperature range (250K-400K). Lastly, a thorough comparative assessment has been performed with existing ammonia gas sensors and findings of this analysis reveals that proposed sensor is highly sensitive and a promising contender for ammonia sensing.