Performance Comparison Between Bulk and SOI Junctionless Transistors

The design and characteristics of a junctionless (JL) bulk FinFET were compared with the silicon-on-insulator (SOI) JL nanowire transistor (JNT) using 3-D quantum transport device simulation. The JL bulk FinFET exhibits a favorable on/offcurrent ratio and short-channel characteristics by reducing the effective channel thickness that is caused by the channel/substrate junction. The drain-induced barrier lowering and the subthreshold slope are about 40 mV and 73 mV/dec, respectively, with an on/offcurrent ratio of 10
⁵
at
W
= 10 nm. The JL bulk FinFET is less sensitive to the channel thickness than the SOI JNT. Furthermore, the threshold voltage
V
_th
of the JL bulk FinFET can be easily tuned by varying substrate doping concentration
N
_sub
. The modulation range of
V
_th
as
N
_sub
changes from 10
¹⁸
to 10
¹⁹
cm
^-3
, which is around 30%.