An ultrasensitive gas nanosensor based on a dual-gate Schottky barrier CNT-FET with an all-terminal gas-sensitive design: a three-dimensional quantum simulation study

In this paper, we propose a new gas nanosensor based on a dual-gate Schottky barrier carbon nanotube field-effect transistor (DG SB-CNTFET) endowed with an all-terminal gas-sensitive configuration, investigated through full quantum-mechanical simulations. The numerical modeling is performed using the non-equilibrium green's function formalism combined with a pz-orbital nearest-neighbor tight-binding approach to describe quantum transport in SB CNTFETs. Full three-dimensional (3D) electrostatics is incorporated by self-consistently solving the Poisson equation. The sensing principle relies on gas-induced variations in the metal work function at all terminals. The 3D quantum simulation study covers transfer characteristics, potential profiles, charge density distributions, transmission coefficients, and sensitivity in both current-mode and pseudo-threshold voltage-shift mode. Four device configurations are investigated: (i) only the source terminal is sensitive, (ii) both source and drain are sensitive, (iii) source, drain, and top-gate are sensitive, and (iv) all terminals, including the back-control gate, are sensitive. The potential for sensitivity enhancement through coupling capacitance engineering is also examined. Results show that the all-terminal gas-sensitive configuration yields a substantial improvement in the constant-current gate voltage shift, enabling the detection of extremely low gas pressures. These findings establish the proposed DG SB-CNTFET-based nanosensor as a strong candidate for next-generation ultra-sensitive gas detection systems, where compact size, low power consumption, and exceptional sensitivity are critical requirements.