Enhanced VOC sensing performance of MWCNT-CuO/ZnO nanocomposite based vertical TFET

This study proposes a high-performance vertical tunnel field-effect transistor (VTFET)-based gas sensor incorporating a nanocomposite channel of multi-walled carbon nanotubes (MWCNTs) combined with CuO/ZnO bilayers. The design leverages the enhanced surface area, superior carrier transport, and strong gate coupling enabled by the vertical configuration to significantly improve gas detection sensitivity. The sensing mechanism is based on modulation of the drain current due to variations in the gate metal's work function upon exposure to volatile organic compounds (VOCs). These changes alter the surface potential and tunneling barrier, producing detectable shifts in the electrical characteristics without relying solely on threshold voltage modulation. Among the analytes examined, ethanol exhibited the highest sensitivity, with a 2.61 % increase in ON-current for a gate work function shift from 45 meV to 200 meV, followed by methanol (2.32 %) and acetone (2.12 %). The sensor achieves a steep subthreshold swing and an exceptionally high I_ON/I_OFF ratio of ∼10¹², indicating excellent switching behaviour and ultra-low leakage. It operates with a maximum threshold voltage of 0.8 V for ethanol detection and maintains low power consumption due to its efficient band-to-band tunneling process. The use of CMOS-compatible materials such as HfO₂, CuO, ZnO, and MWCNTs supports scalable fabrication and cost efficiency. These features make the proposed sensor a strong candidate for real-time VOC detection in various domains, including environmental monitoring, industrial safety, biomedical diagnostics, and automotive applications.