Investigation of a Gate Stack Gate-All-Around Junctionless Nanowire Field-Effect Transistor for Oxygen Gas Sensing

The design and analysis of a gate stack gate-all-around junctionless nanowire field-effect transistor (GAA-JL-NWFET) with a catalytic metal as gate contact for oxygen gas sensing is presented in this study. An n-channel GAA-JL-NWFET design using gold (Au) as the gate metal electrode is employed for oxygen sensing by utilizing appropriate work function values, which interact with oxygen gas and change the device's electrical properties. This work focuses on changes in temperature (300-500 K) and Au metal gate work function (5.05-5.20 eV) to investigate the presence of oxygen molecules and their impact on the GAA-JL-NWFET gas sensor performance. Changes in the surface potential, threshold voltage, hole concentration, electron concentration, subthreshold voltage, electric field, and drain current using the ATLAS TCAD simulator are investigated for the adsorption of gas molecules to determine the electrical characteristics of the proposed device. Changes in threshold voltage (Vth), switching ratio, and subthreshold current sensitivity (SIOFF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S_{{I_{{{\text{OFF}}}} }}$$\end{document}) can be considered as sensitivity parameters for sensing oxygen gas molecules. The results reveal that as the Au work function shifts at the gate by 100 mV, the sensitivity (SIOFF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S_{{I_{{{\text{OFF}}}} }}$$\end{document}) enhancement using gate stack GAA-JL-NWFET-based oxygen gas sensors compared to GAA-MOSFET and conventional MOSFET are 15.13% and 88.31%, respectively. Based on our simulation results, the proposed device offers excellent sensitivity, low power consumption, and a fast response time, making it an appropriate candidate for oxygen gas sensing, including environmental monitoring, medical diagnosis, and industrial safety.