Simulating quantum transport in nanoscale transistors: Real versus mode-space approaches

In this article, we present a computationally efficient, two-dimensional quantum mechanical simulation scheme for modeling electron transport in thin body, fully depleted, n-channel, silicon-on-insulator transistors in the ballistic limit. The proposed simulation scheme, which solves the nonequilibrium Green’s function equations self-consistently with Poisson’s equation, is based on an expansion of the active device Hamiltonian in decoupled mode space. Simulation results from this method are benchmarked against solutions from a rigorous two-dimensional discretization of the device Hamiltonian in real space. While doing so, the inherent approximations, regime of validity and the computational efficiency of the mode-space solution are highlighted and discussed. Additionally, quantum boundary conditions are rigorously derived and the effects of strong off-equilibrium transport are examined. This article shows that the decoupled mode-space solution is an efficient and accurate simulation method for modeling electron transport in nanoscale, silicon-on-insulator transistors.