Investigation of DC Characteristics in Polysilicon Nanowire Tunneling Field-Effect Transistors

Abstract

We simulated polysilicon nanowire tunneling field-effect transistors (poly-Si NW TFETs) for ultra-low power applications. DC characteristics (threshold voltage(Vth), ambipolar effect, on-current(Ion)) of poly-Si NW TFETs were investigated when a single grain boundary (SGB) existed in the channel region. Poly-Si NW TFETs were analyzed using 3-D numerical simulations in terms of different locations and sizes of the SGB. As the SGB was closer to the source/channel junction, longer source-side tunneling path increased Vth but decreased Ion because the captured electrons at the acceptor-like states in the SGB shift conduction band upward at on-state condition. On the other hand, as the SGB was closer to the channel/drain junction, longer drain-side tunneling path decreased ambipolar effect because the captured holes at the donor-like states in the SGB shift valence band downward at reverse-bias condition. In addition, the wider SGBs at the source/channel and the channel/drain junctions induced the longer tunneling path, and increased Vth and decreased Ion and ambipolar effect at on-state and reverse bias conditions, respectively.