Comparison of numerical quantum device models

The Wigner equation and non-equilibrium Green´s functions are two formalisms widely used in quantum device simulation. The Wigner equation, commonly solved by finite difference methods, is solved in this work by a recently developed Monte Carlo method. This method resolves both quantum interference and dissipation effects due to scattering with equal accuracy. Both limits, namely the pure quantum ballistic case and the scattering-dominated classical case are treated properly. A comparison of the Wigner MC solver and NEMO-ID is presented. Resonant tunneling diodes from the literature are chosen as benchmark devices. Current/voltage characteristics are compared for different temperatures and the effect of scattering on the current and the charge distribution is shown. Practical device simulation limitations of the Wigner MC method are discussed. Provided that numerical parameters of the Wigner MC method such as the coherence length and the grid size are chosen properly, results are obtained in good quantitative agreement with NEMO-1D.