Subthreshold Swing in Silicon Gate-All-Around Nanowire and Fully Depleted SOI MOSFETs at Cryogenic Temperature

Subthreshold swing (SS) in a silicon gate-all-around (GAA) nanowire MOSFET with zero body factor is examined from room temperature (RT) down to 4 K. A fully depleted (FD) SOI MOSFET is also evaluated. The values of SS of both transistors decrease in proportional to temperature (T) but start to saturate below 18K, similar to transistors with non-zero body factor in the literature, indicating that the body factor is not related to the SS saturation phenomena at very low temperatures.