Origin of Device Performance Enhancement of Junctionless Accumulation-Mode (JAM) Bulk FinFETs With High- $\kappa $ Gate Spacers

In this letter, we investigated the junctionless accumulation-mode (JAM) bulk FinFETs with high-κ gate spacers showing enhanced device performance in SS, DIBL, and ON/OFF current ratio. We found that origin of the ON-state current enhancement was reduction of the initial energy barrier between the source and channel, and reason for the OFF-state current reduction was LG extension caused by the fringing field through high-κ gate spacers. The OFF-state leakage current decreased by over one order of magnitude. The ON-state current was remarkably enhanced by 180% over that of low-κ gate spacers. The high-κ gate spacer is indispensable for enhancing the performance of the JAM field-effect transistor in a sub 20-nm -gate length regime.