GaSb/Si heterojunction segmented-channel vertical-TFET for high-sensitivity gas sensing in biomedical and industrial environments

Metal-oxide-semiconductor (MOS) based gas sensors have become an essential tool in environmental protection and medical analysis. It is due to their low cost, high reliability, and fast response time. In this reported work, a GaSb/Si heterojunction segmented-channel vertical tunnel field effect transistor (HSC-VTFET) has been proposed for high-sensitivity gas sensing. In the proposed structure, a segmented channel profile and low band gap gallium antimonide (GaSb) material has been adopted as the source material. This facilitates better electron tunneling across the barrier which improves overall sensitivity. Cobalt (Co), silver (Ag), and palladium (Pd) metals are employed as gate electrodes for the selective detection of ammonia (NH_₃), oxygen (O_₂), and hydrogen (H_₂) respectively. The presence of target gas molecules causes variation in the gate-metal work function. The effects of gas molecule adsorption at the gate metal surface on the surface potential, electric field, threshold voltage, and energy band structure of HSC-VTFET are systematically analyzed using the Silvaco Atlas TCAD tool. The proposed device has low OFF current (I_OFF) of 6.653 × 10^− 19 A/µm, high ON current (I_ON) of 1.077 × 10^− 4 A/µm, and high I_ON/I_OFF current ratio in the range of 10¹⁴. Temperature reliability analysis of the proposed device shows almost stable performance. The sensitivity of the proposed GaSb/Si HSC-VTFET is improved compared with previously reported devices.