Robust cryogenic ab-initio quantum transport simulation for LG = 10 nm nanowire

In this paper, we propose a simulation methodology for robust and accurate ab-initio quantum transport simulation down to 3 K of an n-type Si nanowire. This is important to understand the subthreshold swing (SS) at cryogenic temperature. We show that for LG = 10 nm, the SS is fully dominated by direct tunneling at cryogenic temperature, which is the first time to be demonstrated using ab-initio simulation, to the best of our knowledge. We propose a method to achieve more than 2x speed up in the simulation time and achieve convergence at high gate biases. It is also shown that from the leakage perspective, there is no advantage in operating LG = 10 nm transistor below 77 K.