Investigations of junctionless nanowire transistors with non-uniform channel

In this paper, the effects of non-uniform channel (NUC) in junctionless nanowire transistors (JNTs) are investigated and compared with those in inversion-mode field effect transistors (IMFETs) using three-dimensional simulations. The results show that, the variation of threshold voltage V_t in JNTs is 1.7 times of that in IMFETs and the fluctuation of off-state current I_off is 2.8 times, which is mainly because that JNTs have bulk conduction channels and higher doping concentration in the channels. Hence, the process fluctuation for JNTs must be 30% or even smaller of that for IMFETs for similar performance variation. Furthermore, we conclude a formula based on the results to limit the variation of channel width.