Tunnel field-effect transistor with two gated intrinsic regions

In this paper, we propose and validate (using simulations) a novel design of silicon tunnel field-effect transistor (TFET), based on a reverse-biased p+-p-n-n+ structure. 2D device simulation results show that our devices have significant improvements of switching performance compared with more conventional devices based on p-i-n structure. With independent gate voltages applied to two gated intrinsic regions, band-to-band tunneling (BTBT) could take place at the p-n junction, and no abrupt degenerate doping profile is required. We developed single-side-gate (SSG) structure and double-side-gate (DSG) structure. SSG devices with HfO2 gate dielectric have a point subthreshold swing of 9.58 mV/decade, while DSG devices with polysilicon gate electrode material and HfO2 gate dielectric have a point subthreshold swing of 16.39 mV/decade. These DSG devices have ON-current of 0.255 μA/μm, while that is lower for SSG devices. Having two nano-scale independent gates will be quite challenging to realize with good uniformity across the wafer and the improved behavior of our TFET makes it a promising steep-slope switch candidate for further investigations.