Pocket assisted stepped tunneling to improve the band-to-band tunneling effect of nanotube TFETs

This paper proposes a stepped tunneling nanotube tunnel field-effect transistor (ST-NT-TFET). By introducing a source-side doped pocket with the same polarity within the TFET channel and employing asymmetric gate bias modulation, the device transforms point tunneling into a stepped tunneling pathway, thereby enhancing the band-to-band tunneling effect. Using Si 0.5 Ge 0.5 as the source, the electrical characteristics and high-frequency performance of the ST-NT-TFET were investigated under different pocket parameters. Simulation results demonstrate that compared to conventional NT-TFETs with identical channel dimensions, the ST-NT-TFET achieves a 50% (p-TFET) and 109% (n-TFET) increase in on-state current, 92% (p) and 48% (n) enhancements in cut-off frequency, and 78% (p) and 66% boosts in gain-bandwidth product. The intrinsic delay is reduced by 55% (p) and 83% (n), while the effective drive current increases by 40% (p) and 135% (n). Circuit simulations further reveal that inverters constructed with ST-NT-TFETs exhibit a 27% increase in noise margin, 53% (fall time) and 31% (rise time) reductions in switching times, and an 11-stage ring oscillator frequency increased by 3.8 times (280% improvement). • Same-source doping pocket in NT-TFET creates stepped tunneling, boosting I o n by 50% (p) and 109% (n). • Asymmetric shell/core gate controls stepped tunneling, reducing gate capacitance and boosting f T ( ↑ 92% p, ↑ 48% n) and GBP ( ↑ 78% p, ↑ 66% n). • Same-source doping pocket enables n/p-TFET compatibility with balanced current matching, achieving high-performance CMOS-like inverters.