An ultra steep slope and low voltage split gate oxide dual gate vertical TFET based multi gas sensor

This work presents an ultra steep slope and low voltage split gate oxide dual gate vertical TFET (USS-LV-SGO-VTFET) based multi gas sensor for the detection of ammonia (NH 3 ), oxygen (O 2 ), and hydrogen (H 2 ) with different work-function variations of 0–200 meV at VDS=1 V and VGS=1.5 V. The vertical architecture employs a dual-gate configuration to achieve strong electrostatic control and effective modulation of band-to-band tunneling (BTBT) under gas-induced gate work-function variations. The sensing mechanism is governed by gas adsorption induced work function shifts in the range of 50–200 meV, which directly modulate the tunneling window at the source–channel(S-C) junction. The optimized device exhibits pronounced variations in transfer characteristics with increasing work function ( Δ WF ), confirming a significant improvement in sensitivity. Cobalt (Co), Silver (Ag), and Palladium (Pd), with work functions of 4.7 eV, 5.0 eV, and 5.1 eV, respectively, are employed as catalytic gate materials for selective NH 3 , O 2 , and H 2 detection. The USS-LV-SGO-VTFET gas sensor has an ultra-low OFF current around 10⁻¹⁸ A/ μ m and a sharp subthreshold swing of 17.5 mV/dec. It achieves ON current sensitivities of 0.594 for NH 3 , 0.933 for O 2 , and 0.987 for H 2 with a work-function variation of 200 meV. The dual-gate vertical structure greatly enhances tunneling barrier modulation during gas exposure, which increases BTBT probability and improves ON-state current and energy-band analysis. These findings indicate that the USS-LV-SGO-VTFET design offers a low-power, efficient platform for next-generation gas sensing applications.