  Junctionless transistors made of silicon have previously been demonstrated
experimentally and by simulations. Junctionless devices do not require
fabricating an abrupt source-drain junction and thus can be easier to implement
in aggressive geometries. In this paper, we explore a similar architecture for
aggressively scaled devices with the channel consisting of doped carbon
nanotubes (CNTs). Gate all around (GAA) field effect transistor (FET)
structures are investigated for n- and p-type doping. Current-voltage
characteristics and sub-threshold characteristics for a CNTbased junctionless
FET is compared with a junctionless silicon nanowire (SiNW) FET with comparable
dimensions. Despite the higher on-current of the CNT channels, the device
characteristics are poorer compared to the silicon devices due to the smaller
CNT band gap.
