A Quantum Monte Carlo (QMC) method taking into account both interference and dissipation effects is presented. The method solves the space-dependent Wigner equation which includes semi-classical scattering via the Boltzmann collision operator. The classical force term is separated from the Wigner potential and included in the Liouville operator on the left hand side. Using the Wigner potential as an additional scattering source is not straight forward because it assumes positive and negative values. To permit a probabilistic interpretation, the Wigner potential is expressed as a difference of two positive functions. The Wigner function is represented by a set of weighted particles. Scattering from the negative part of the Wigner potential results in a sign change of the weight. A peculiarity of the MC method is that the number of numerical particles increases, while the total charge is strictly conserved. In the simulation numerical particles are continuously removed by annihilation of neighboring particles of opposite weight. A resonant tunneling diode (RTD) has been simulated using the new QMC method. Polar optical and acoustic deformation potential scattering are included. The results clearly show that both semi-classical and quantum transport features are well treated by the method.
Journal: TechConnect Briefs
Volume: 2, Technical Proceedings of the 2003 Nanotechnology Conference and Trade Show, Volume 2
Published: February 23, 2003
Pages: 190 - 193
Industry sectors: Advanced Materials & Manufacturing | Sensors, MEMS, Electronics
Topics: Modeling & Simulation of Microsystems