As electronics advance toward higher performance and adaptability in extreme environments, traditional metal-oxide-semiconductor field-effect transistors (MOSFETs) face challenges due to physical constraints such as Boltzmann's law and short-channel effects. Nanoscale air channel transistors (NACTs) present a promising alternative, leveraging their vacuum-like channel and Fowler-Nordheim tunneling characteristics. In this study, a novel circular gate NACT (CG-NACT) is purposed, fabricated on a 4-inch silicon-based wafer using a CMOS-compatible process. By employing an innovative gate control mechanism, the transistors achieve an ultralow SS of only 0.15 mV dec