Performance Analysis of the Ultrathin-Body L-Shaped Tunnel FET for Hydrogen Gas Detection—A Device Simulation-Based Approach

In this work, an ultrathin-body L-shaped (UTBL)-catalytic metal gated (CMG)-tunnel field-effect transistor (TFET) architecture is extensively studied for hydrogen (H2) gas sensing application using numerical device simulation. The inherently superior subthreshold electrostatic integrity of ultrathin-body (UTB) structure as well as the vertical tunneling (VT)-dominated carrier transport of the sensor device is exploited to augment the transduction efficiency during H2 gas detection, which is quantified from the drain current sensitivity. Next, the underlying device physics of the proposed UTBL-CMG-TFET is methodically analyzed and exploited for systematic performance optimization by tuning the device’s structural parameters, emphasizing the source doping and channel thickness. Finally, the comparative performance study demonstrates that the room temperature H2 gas sensing performance of the optimized UTBL-CMG-TFET significantly supercedes the performances of conventional CMG-TFET and CMG-metal-oxide–semiconductor field-effect transistor (MOSFET) as well as previously reported TFET-based H2 gas sensors. The structurally optimized UTBL-CMG-TFET demonstrates an average subthreshold swing (SS) of ~24.2 mV/decade over four decades (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-{12}}$ </tex-math></inline-formula>–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-{8}}$ </tex-math></inline-formula>A/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m) of subthreshold current,<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small>-state/<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small>-state current ratio of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10^{{7}}$ </tex-math></inline-formula>, and a notably larger <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{{60}}$ </tex-math></inline-formula> (current @ 60 mV/decade) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 2 \times \; 10^{-{8}}$ </tex-math></inline-formula>A/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m leading to an extremely large drain current sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 3.0 \times \; 10^{{5}}$ </tex-math></inline-formula>, which radically supercede the performance of previously reported silicon/silicon-germanium-based CMG-MOSFET and TFET-based H2 gas sensors.