Simulation of the process variation in negative capacitance virtual-source carbon nanotube FET devices and circuits

Abstract

We have reported the impact of process variation of virtual- source carbon nanotube field-effect transistor (VS-CNFET) device externally connected to the epitaxial ferroelectric (FE) capacitor through the spectre parametric simulation. We have found that the FE materials with high remnant polarization produces better transfer characteristics and suppressed short channel effects (SCE). The increase in the ferroelectric thickness (t_fe) has brought out the good impact of 4x improvement in ON current and reduced subthreshold swing of 40 mV/decade. The ON current has been increased with increase in thickness of ferroelectric material and has followed a monotonic trend, where the leakage current becomes a major concern and optimization of crucial parameters such as a diameter of the nanotube has given importance. Relative to the VS- CNFET model, the negative capacitance VS-CNFET model has stacked in ring oscillator (RO) displays immune to delay variation and produces better switching characteristics.