MOSFET-Like Carbon Nanotube Field Effect Transistor Model

An analytical model that captures the essence of physical processes in a CNTFET's is presented. The model covers seamlessly the whole range of transport from drift-diffusion to ballistic. It has been clarified that the intrinsic speed of CNT's is governed by the transit time of electrons. Although the transit time is more dependent on the saturation velocity than on the weak-field mobility, the feature of high-electron mobility is beneficial in the sense that the drift velocity is maintained always closer to the saturation velocity, at least on the drain end of the transistor where electric field is necessarily high and controls the saturation current. The results obtained are applied to the modeling of the current-voltage characteristic of a carbon nanotube field effect transistor. The channel-length modulation is shown to arise from drain velocity becoming closer to the ultimate saturation velocity as the drain voltage is increased.