Energy Efficient GaSb/Si –Hetero DG Vertical TFET based O2, H2 and NH3 Gas Sensor for Healthcare and Environmental Monitoring

Highly sensitive and selective sensor technologies are required for gas sensing to meet public health, industrial safety, and environmental monitoring requirements. The proposed GaSb/Si hetero double gate vertical tunnel field transistor (V-TFET) incorporates tunable gate work function engineering to detect O₂, H₂, and NH₃ gases. Here, vertical tunneling will lower the subthreshold slope and increase device sensitivity. A stacked high-κ (TiO₂)/SiO₂ gate oxide with metal electrodes on both sides significantly improves the device's electrostatic control. Further lowering the energy bandgap at the GaSb/Si hetero interface reduces the tunneling barrier, improving its overall current drive and switching performance. In this study, the effects of gate metal surface gas molecule adsorption on the electric field (E _f ), energy band structure, threshold voltage, and surface potential were deeply investigated. Gate metals: cobalt (WF = 4.7 eV), silver (WF = 5.0 eV), and palladium (WF = 5.1 eV) were employed for the detection of NH ₃ , O ₂ , and H ₂ gases respectively. The I _ON /I _OFF current ratio for unexposed cobalt (~ 1.08 ×10 ¹³ ), silver (~ 4.02 ×10 ¹² ), and palladium (~ 1.76 ×10 ¹² ) is found to be higher than for exposed cobalt (~ 7.37×10 ¹² ), silver (~ 6.07×10 ¹¹ ), and palladium (~ 1.58×10 ¹¹ ) with an adequate SS (18.22 mV/dec).