Stochastic analysis of surface roughness models in quantum wires

We present a signed particle computational approach for the Wigner transport model and use it to analyze the electron state dynamics in quantum wires focusing on the effect of surface roughness. Usually surface roughness is considered as a scattering model, accounted for by the Fermi Golden Rule, which relies on approximations like statistical averaging and in the case of quantum wires incorporates quantum corrections based on the mode space approach. We provide a novel computational approach to enable physical analysis of these assumptions in terms of phase space and particles. Utilized is the signed particles model of Wigner evolution, which, besides providing a full quantum description of the electron dynamics, enables intuitive insights into the processes of tunneling, which govern the physical evolution. It is shown that the basic assumptions of the quantum-corrected scattering model correspond to the quantum behavior of the electron system. Of particular importance is the distribution of the density: Due to the quantum confinement, electrons are kept away from the walls, which is in contrast to the classical scattering model. Further quantum effects are retardation of the electron dynamics and quantum reflection. Far from equilibrium the assumption of homogeneous conditions along the wire breaks even in the case of ideal wire walls

A Multi-Scale Simulation Study of the Strained Si Nanowire FETs

In this work, we study 2.1nm-diameter uniaxial strained Si gate-all-around nanowire field-effect transistors, focusing on the electron mobility and the variability due to random discrete dopants (RDDs). Firstly, we extract the electron effective masses under various strains from Density Functional Theory (DFT) simulations. Secondly, we present the impact of the strain on the electron mobility in the Si nanowire using the Kubo-Greenwood formalism with a set of multi-subband phonon, surface roughness, and ionized impurity scattering mechanisms. Finally, we perform quantum transport simulations to investigate the effect of RDD on the threshold voltage and ON-state current variation