FEM Model of Wraparound CNTFET With Multi-CNT and Its Capacitance Modeling

The wraparound gate carbon nanotube field-effect transistor (CNTFET) has the advantage of more accurately controlled channel than the top-gate CNTFET. A 3-D simulation is performed using the finite-element method (FEM) to model the wraparound CNTFET with multi-CNT channels. Analytical expressions to model various capacitances of the same device are also derived from capacitances for the 1-D FET with multiple cylindrical conducting channels incorporating screening effect due to multiple CNT. Various capacitances thus obtained exhibit remarkable improvement over the planar top-gate device with multiple conducting channels. This is attributed to the charge enhancement and the better charge confinement in the channel of the wraparound CNTFET with multi-CNT channels. Capacitances are also extracted from the proposed FEM model. The extracted capacitances are in excellent agreement with the capacitances obtained from the analytical model presented in this study.