Back biasing effects in tri-gate junctionless transistors

•The back bias effect on junctionless transistors (JLTs) has been investigated.•JLTs are more sensitive to back biasing compared to inversion-mode device.•The effective mobility of JLT is enhanced below flat band voltage by back bias.•The back bias effect in narrow JLTs is suppressed.•2-D numerical simulation successfully reconstruct of the trend of back bias effects. The back bias effect on tri-gate junctionless transistors (JLTs) has been investigated using experimental results and 2-D numerical simulations, compared to inversion-mode (IM) transistors. Results show that JLT devices are more sensitive to back biasing due to the bulk conduction. It is also shown that the effective mobility of JLT is significantly enhanced below flat band voltage by back bias. However, in extremely narrow JLTs, the back bias effect is suppressed by reduced portion of bulk conduction and strong sidewall gate controls. 2-D numerical charge simulation well supports experimental results by reconstructing the trend of back bias effects.