Channel width dependent subthreshold operation of tri-gate junctionless transistors

•Subthreshold operation of tri-gate junctionless transistors (JLTs) with various effective width (Weff) was investigated.•Physical operation mechanism on the subthreshold regime of JLTs was also discussed in detail.•The on current to off current ratio (Ion/Ioff) and subthreshold swing (SS) of JLTs were varied dramatically as changing Weff.•Remained carriers at the bottom caused a higher off-current, a deviated shape of log10(n) derivatives.•In addition, a better immunity against short channel effects (SCEs) in JLTs was proven.