A fast and stable Poisson-Schrödinger solver for the analysis of carbon nanotube transistors

When the coupled Schrödinger-Poisson system is solved iteratively with appropriate numerical damping, convergence problems are likely to occur. We show that these problems are due to inappropriate energy discretization for evaluating the carrier concentration. By using an adaptive method the self-consistent loop becomes stable, and most of the simulations converge in a few iterations. We applied this approach to investigate the behavior of carbon nanotube field effect transistors.