In this paper, the effect of gate workfunction variation on electron concentration at depletion and inversion as a function of applied gate voltage for 100 nm gate length silicon-on-insulator (SOI) junctionless (JLT) and junction (JT) transistors are investigated. It shows that the JLT device is properly function and achieving full-depletion without losing gate controllability at higher gate workfunction of more than 5.0 eV whereas the designated JT device is more wider range, ranging from low, mid-gap or high workfunction.